diff --git a/infra/LocaleGenerator.php b/infra/LocaleGenerator.php
index b880f6e61d..e996f42725 100644
--- a/infra/LocaleGenerator.php
+++ b/infra/LocaleGenerator.php
@@ -86,7 +86,13 @@ public function generateLocales(): void
     protected function buildConfigFileForLocale(string $column, string $locale): void
     {
         $language = $this->localeTranslations->getCell($column . self::ENGLISH_LANGUAGE_NAME_ROW)->getValue();
+        if (!is_string($language)) {
+            throw new Exception('Non-string language value at ' . $column . self::ENGLISH_LANGUAGE_NAME_ROW);
+        }
         $localeLanguage = $this->localeTranslations->getCell($column . self::LOCALE_LANGUAGE_NAME_ROW)->getValue();
+        if (!is_string($localeLanguage)) {
+            throw new Exception('Non-string locale language value at ' . $column . self::LOCALE_LANGUAGE_NAME_ROW);
+        }
         $configFile = $this->openConfigFile($locale, $language, $localeLanguage);
 
         $this->writeConfigArgumentSeparator($configFile, $column);
@@ -96,6 +102,9 @@ protected function buildConfigFileForLocale(string $column, string $locale): voi
         foreach ($this->errorCodeMap as $errorCode => $row) {
             $translationCell = $this->localeTranslations->getCell($column . $row);
             $translationValue = $translationCell->getValue();
+            if ($translationValue !== null && !is_string($translationValue)) {
+                throw new Exception('Non-string translation value at ' . $column . $row);
+            }
             if (!empty($translationValue)) {
                 $errorCodeTranslation = "{$errorCode} = {$translationValue}" . self::EOL;
                 fwrite($configFile, $errorCodeTranslation);
@@ -114,6 +123,9 @@ protected function writeConfigArgumentSeparator($configFile, string $column): vo
     {
         $translationCell = $this->localeTranslations->getCell($column . self::ARGUMENT_SEPARATOR_ROW);
         $localeValue = $translationCell->getValue();
+        if ($localeValue !== null && !is_string($localeValue)) {
+            throw new Exception('Non-string locale value at ' . $column . self::CURRENCY_SYMBOL_ROW);
+        }
         if (!empty($localeValue)) {
             $functionTranslation = "ArgumentSeparator = {$localeValue}" . self::EOL;
             fwrite($configFile, $functionTranslation);
@@ -127,6 +139,9 @@ protected function writeConfigCurrencySymbol($configFile, string $column): void
     {
         $translationCell = $this->localeTranslations->getCell($column . self::CURRENCY_SYMBOL_ROW);
         $localeValue = $translationCell->getValue();
+        if ($localeValue !== null && !is_string($localeValue)) {
+            throw new Exception('Non-string locale value at ' . $column . self::CURRENCY_SYMBOL_ROW);
+        }
         if (!empty($localeValue)) {
             $functionTranslation = "currencySymbol = {$localeValue}" . self::EOL;
             fwrite($configFile, '##' . self::EOL);
@@ -141,13 +156,22 @@ protected function writeConfigCurrencySymbol($configFile, string $column): void
     protected function buildFunctionsFileForLocale(string $column, string $locale): void
     {
         $language = $this->functionNameTranslations->getCell($column . self::ENGLISH_LANGUAGE_NAME_ROW)->getValue();
+        if (!is_string($language)) {
+            throw new Exception('Non-string language value at ' . $column . self::ENGLISH_LANGUAGE_NAME_ROW);
+        }
         $localeLanguage = $this->functionNameTranslations->getCell($column . self::LOCALE_LANGUAGE_NAME_ROW)
             ->getValue();
+        if (!is_string($localeLanguage)) {
+            throw new Exception('Non-string locale language value at ' . $column . self::LOCALE_LANGUAGE_NAME_ROW);
+        }
         $functionFile = $this->openFunctionNameFile($locale, $language, $localeLanguage);
 
         foreach ($this->functionNameMap as $functionName => $row) {
             $translationCell = $this->functionNameTranslations->getCell($column . $row);
             $translationValue = $translationCell->getValue();
+            if ($translationValue !== null && !is_string($translationValue)) {
+                throw new Exception('Non-string translation value at ' . $column . $row);
+            }
             if ($this->isFunctionCategoryEntry($translationCell)) {
                 $this->writeFileSectionHeader($functionFile, "{$translationValue} ({$functionName})");
             } elseif (!array_key_exists($functionName, $this->phpSpreadsheetFunctions) && substr($functionName, 0, 1) !== '*') {
diff --git a/samples/Basic/13_Calculation.php b/samples/Basic/13_Calculation.php
index f7ea7aa874..3c215315b9 100644
--- a/samples/Basic/13_Calculation.php
+++ b/samples/Basic/13_Calculation.php
@@ -157,8 +157,9 @@
 $helper->log('Calculated data');
 for ($col = 'B'; $col != 'G'; ++$col) {
     for ($row = 14; $row <= 41; ++$row) {
+        $formula = $spreadsheet->getActiveSheet()->getCell($col . $row)->getValue();
         if (
-            (($formula = $spreadsheet->getActiveSheet()->getCell($col . $row)->getValue()) !== null)
+            is_string($formula)
             && ($formula[0] == '=')
         ) {
             $helper->log('Value of ' . $col . $row . ' [' . $formula . ']: ' . $spreadsheet->getActiveSheet()->getCell($col . $row)->getCalculatedValue());
diff --git a/samples/Basic/13_CalculationCyclicFormulae.php b/samples/Basic/13_CalculationCyclicFormulae.php
index c48e736e42..45a9f5b6a5 100644
--- a/samples/Basic/13_CalculationCyclicFormulae.php
+++ b/samples/Basic/13_CalculationCyclicFormulae.php
@@ -22,8 +22,9 @@
 $helper->log('Calculated data');
 for ($row = 1; $row <= 2; ++$row) {
     for ($col = 'A'; $col != 'C'; ++$col) {
+        $formula = $spreadsheet->getActiveSheet()->getCell($col . $row)->getValue();
         if (
-            (($formula = $spreadsheet->getActiveSheet()->getCell($col . $row)->getValue()) !== null)
+            is_string($formula)
                 && ($formula[0] == '=')
         ) {
             $helper->log('Value of ' . $col . $row . ' [' . $formula . ']: ' . $spreadsheet->getActiveSheet()->getCell($col . $row)->getCalculatedValue());
diff --git a/samples/Basic/31_Document_properties_write.php b/samples/Basic/31_Document_properties_write.php
index bdce86dde5..4fdd1cfa61 100644
--- a/samples/Basic/31_Document_properties_write.php
+++ b/samples/Basic/31_Document_properties_write.php
@@ -56,7 +56,7 @@
     $propertyValue = $spreadsheet->getProperties()->getCustomPropertyValue($customProperty);
     $propertyType = $spreadsheet->getProperties()->getCustomPropertyType($customProperty);
     if ($propertyType == Properties::PROPERTY_TYPE_DATE) {
-        $formattedValue = date('d-M-Y H:i:s', (int) $propertyValue);
+        $formattedValue = is_numeric($propertyValue) ? date('d-M-Y H:i:s', (int) $propertyValue) : '*****INVALID*****';
     } elseif ($propertyType == Properties::PROPERTY_TYPE_BOOLEAN) {
         $formattedValue = $propertyValue ? 'TRUE' : 'FALSE';
     } else {
diff --git a/samples/Basic/31_Document_properties_write_xls.php b/samples/Basic/31_Document_properties_write_xls.php
index f3a48f95d2..5c4815519c 100644
--- a/samples/Basic/31_Document_properties_write_xls.php
+++ b/samples/Basic/31_Document_properties_write_xls.php
@@ -56,7 +56,7 @@
     $propertyValue = $spreadsheet->getProperties()->getCustomPropertyValue($customProperty);
     $propertyType = $spreadsheet->getProperties()->getCustomPropertyType($customProperty);
     if ($propertyType == Properties::PROPERTY_TYPE_DATE) {
-        $formattedValue = date('d-M-Y H:i:s', (int) $propertyValue);
+        $formattedValue = is_numeric($propertyValue) ? date('d-M-Y H:i:s', (int) $propertyValue) : '*****INVALID*****';
     } elseif ($propertyType == Properties::PROPERTY_TYPE_BOOLEAN) {
         $formattedValue = $propertyValue ? 'TRUE' : 'FALSE';
     } else {
diff --git a/samples/Basic/45_Quadratic_equation_solver.php b/samples/Basic/45_Quadratic_equation_solver.php
index 8e798da2f3..30aabf60f5 100644
--- a/samples/Basic/45_Quadratic_equation_solver.php
+++ b/samples/Basic/45_Quadratic_equation_solver.php
@@ -59,8 +59,12 @@
         $r1Formula = '=IMDIV(IMSUM(-' . $_POST['B'] . ',IMSQRT(' . $discriminant . ')),2 * ' . $_POST['A'] . ')';
         $r2Formula = '=IF(' . $discriminant . '=0,"Only one root",IMDIV(IMSUB(-' . $_POST['B'] . ',IMSQRT(' . $discriminant . ')),2 * ' . $_POST['A'] . '))';
 
-        $helper->log(Calculation::getInstance()->calculateFormula($r1Formula));
-        $helper->log(Calculation::getInstance()->calculateFormula($r2Formula));
+        /** @var string */
+        $output = Calculation::getInstance()->calculateFormula($r1Formula);
+        $helper->log("$output");
+        /** @var string */
+        $output = Calculation::getInstance()->calculateFormula($r2Formula);
+        $helper->log("$output");
         $callEndTime = microtime(true);
         $helper->logEndingNotes();
     }
diff --git a/samples/Calculations/DateTime/DAYS360.php b/samples/Calculations/DateTime/DAYS360.php
index b0e2fdbb13..a9f045f746 100644
--- a/samples/Calculations/DateTime/DAYS360.php
+++ b/samples/Calculations/DateTime/DAYS360.php
@@ -49,9 +49,11 @@
         $worksheet->getCell('E' . $row)->getFormattedValue(),
         $worksheet->getCell('F' . $row)->getFormattedValue()
     ));
-    $helper->log(sprintf(
-        'Days: %d (US) %d (European)',
-        $worksheet->getCell('G' . $row)->getCalculatedValue(),
-        $worksheet->getCell('H' . $row)->getCalculatedValue()
-    ));
+    $helper->log(
+        'Days: '
+        . $worksheet->getCell('G' . $row)->getCalculatedValue()
+        . ' (US) '
+        . $worksheet->getCell('H' . $row)->getCalculatedValue()
+        . ' (European)'
+    );
 }
diff --git a/samples/Calculations/DateTime/EDATE.php b/samples/Calculations/DateTime/EDATE.php
index be6e4d1915..a0efe89806 100644
--- a/samples/Calculations/DateTime/EDATE.php
+++ b/samples/Calculations/DateTime/EDATE.php
@@ -33,11 +33,16 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDateCount; ++$row) {
-    $helper->log(sprintf(
-        '%s and %d months is %d (%s)',
-        $worksheet->getCell('B' . $row)->getFormattedValue(),
-        $worksheet->getCell('C' . $row)->getFormattedValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-        $worksheet->getCell('D' . $row)->getFormattedValue()
-    ));
+    /** @var null|bool|float|int|string */
+    $calc = $worksheet->getCell('D' . $row)->getCalculatedValue();
+    $helper->log(
+        $worksheet->getCell('B' . $row)->getFormattedValue()
+        . ' and '
+        . $worksheet->getCell('C' . $row)->getFormattedValue()
+        . ' months is '
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('D' . $row)->getFormattedValue()
+        . ')'
+    );
 }
diff --git a/samples/Calculations/DateTime/EOMONTH.php b/samples/Calculations/DateTime/EOMONTH.php
index e0b7568a01..27882b97c6 100644
--- a/samples/Calculations/DateTime/EOMONTH.php
+++ b/samples/Calculations/DateTime/EOMONTH.php
@@ -33,11 +33,14 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDateCount; ++$row) {
-    $helper->log(sprintf(
-        '%s and %d months is %d (%s)',
-        $worksheet->getCell('B' . $row)->getFormattedValue(),
-        $worksheet->getCell('C' . $row)->getFormattedValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-        $worksheet->getCell('D' . $row)->getFormattedValue()
-    ));
+    $helper->log(
+        $worksheet->getCell('B' . $row)->getFormattedValue()
+        . ' and '
+        . $worksheet->getCell('C' . $row)->getFormattedValue()
+        . ' months is '
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('D' . $row)->getFormattedValue()
+        . ')'
+    );
 }
diff --git a/samples/Calculations/DateTime/NETWORKDAYS.php b/samples/Calculations/DateTime/NETWORKDAYS.php
index 585c04380f..3f0d409a05 100644
--- a/samples/Calculations/DateTime/NETWORKDAYS.php
+++ b/samples/Calculations/DateTime/NETWORKDAYS.php
@@ -56,11 +56,15 @@
 $helper->displayGrid($holidayData);
 
 for ($row = 1; $row <= 12; ++$row) {
-    $helper->log(sprintf(
-        'Between %s and %s is %d working days; %d with public holidays',
-        $worksheet->getCell('A1')->getFormattedValue(),
-        $worksheet->getCell('B' . $row)->getFormattedValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue()
-    ));
+    $helper->log(
+        'Between '
+        . $worksheet->getCell('A1')->getFormattedValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getFormattedValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+        . ' working days; '
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ' excluding public holidays'
+    );
 }
diff --git a/samples/Calculations/DateTime/NOW.php b/samples/Calculations/DateTime/NOW.php
index 858a3162b1..e638f647a3 100644
--- a/samples/Calculations/DateTime/NOW.php
+++ b/samples/Calculations/DateTime/NOW.php
@@ -20,8 +20,10 @@
     ->setFormatCode('yyyy-mm-dd hh:mm:ss');
 
 // Test the formulae
-$helper->log(sprintf(
-    'Today is %f (%s)',
-    $worksheet->getCell('A1')->getCalculatedValue(),
-    $worksheet->getCell('A1')->getFormattedValue()
-));
+$helper->log(
+    'Today is '
+    . $worksheet->getCell('A1')->getCalculatedValue()
+    . ' ('
+    . $worksheet->getCell('A1')->getFormattedValue()
+    . ')'
+);
diff --git a/samples/Calculations/DateTime/TODAY.php b/samples/Calculations/DateTime/TODAY.php
index 031149d597..e36fc9eb82 100644
--- a/samples/Calculations/DateTime/TODAY.php
+++ b/samples/Calculations/DateTime/TODAY.php
@@ -20,8 +20,10 @@
     ->setFormatCode('yyyy-mm-dd');
 
 // Test the formulae
-$helper->log(sprintf(
-    'Today is %d (%s)',
-    $worksheet->getCell('A1')->getCalculatedValue(),
-    $worksheet->getCell('A1')->getFormattedValue()
-));
+$helper->log(
+    'Today is '
+    . $worksheet->getCell('A1')->getCalculatedValue()
+    . ' ('
+    . $worksheet->getCell('A1')->getFormattedValue()
+    . ')'
+);
diff --git a/samples/Calculations/DateTime/WEEKDAY.php b/samples/Calculations/DateTime/WEEKDAY.php
index 7d4b4288b2..df4854dc69 100644
--- a/samples/Calculations/DateTime/WEEKDAY.php
+++ b/samples/Calculations/DateTime/WEEKDAY.php
@@ -47,12 +47,14 @@
 // Test the formulae
 for ($row = 1; $row <= $testDateCount; ++$row) {
     $helper->log(sprintf('(E%d): %s', $row, $worksheet->getCell('E' . $row)->getFormattedValue()));
-    $helper->log(sprintf(
-        'Weekday is: %d (1-7 = Sun-Sat)',
-        $worksheet->getCell('F' . $row)->getCalculatedValue()
-    ));
-    $helper->log(sprintf(
-        'Weekday is: %d (1-7 = Mon-Sun)',
-        $worksheet->getCell('G' . $row)->getCalculatedValue()
-    ));
+    $helper->log(
+        'Weekday is: '
+        . $worksheet->getCell('F' . $row)->getCalculatedValue()
+        . ' (1-7 = Sun-Sat)'
+    );
+    $helper->log(
+        'Weekday is: '
+        . $worksheet->getCell('G' . $row)->getCalculatedValue()
+        . ' (1-7 = Mon-Sun)'
+    );
 }
diff --git a/samples/Calculations/DateTime/YEARFRAC.php b/samples/Calculations/DateTime/YEARFRAC.php
index 81b36435d7..4da0ae0121 100644
--- a/samples/Calculations/DateTime/YEARFRAC.php
+++ b/samples/Calculations/DateTime/YEARFRAC.php
@@ -53,24 +53,29 @@
         $worksheet->getCell('E' . $row)->getFormattedValue(),
         $worksheet->getCell('F' . $row)->getFormattedValue()
     ));
-    $helper->log(sprintf(
-        'Days: %f - US (NASD) 30/360',
-        $worksheet->getCell('G' . $row)->getCalculatedValue()
-    ));
-    $helper->log(sprintf(
-        'Days: %f - Actual',
-        $worksheet->getCell('H' . $row)->getCalculatedValue()
-    ));
-    $helper->log(sprintf(
-        'Days: %f - Actual/360',
-        $worksheet->getCell('I' . $row)->getCalculatedValue()
-    ));
-    $helper->log(sprintf(
-        'Days: %f - Actual/365',
-        $worksheet->getCell('J' . $row)->getCalculatedValue()
-    ));
-    $helper->log(sprintf(
-        'Days: %f - European 30/360',
-        $worksheet->getCell('K' . $row)->getCalculatedValue()
-    ));
+    $helper->log(
+        'Days: '
+        . $worksheet->getCell('G' . $row)->getCalculatedValue()
+        . ' - US (NASD) 30/360'
+    );
+    $helper->log(
+        'Days: '
+        . $worksheet->getCell('H' . $row)->getCalculatedValue()
+        . ' - Actual'
+    );
+    $helper->log(
+        'Days: '
+        . $worksheet->getCell('I' . $row)->getCalculatedValue()
+        . ' - Actual/360'
+    );
+    $helper->log(
+        'Days: '
+        . $worksheet->getCell('J' . $row)->getCalculatedValue()
+        . ' - Actual/365'
+    );
+    $helper->log(
+        'Days: '
+        . $worksheet->getCell('K' . $row)->getCalculatedValue()
+        . ' - European 30/360'
+    );
 }
diff --git a/samples/Calculations/Engineering/BESSELI.php b/samples/Calculations/Engineering/BESSELI.php
index bd5d9b7150..d2c3484381 100644
--- a/samples/Calculations/Engineering/BESSELI.php
+++ b/samples/Calculations/Engineering/BESSELI.php
@@ -18,12 +18,9 @@
 for ($n = 0; $n <= 5; ++$n) {
     for ($x = 0; $x <= 5; $x = $x + 0.25) {
         Calculation::getInstance($spreadsheet)->flushInstance();
-        $worksheet->setCellValue('A1', "=BESSELI({$x}, {$n})");
+        $formula = "BESSELI({$x}, {$n})";
+        $worksheet->setCellValue('A1', "=$formula");
 
-        $helper->log(sprintf(
-            '%s = %f',
-            $worksheet->getCell('A1')->getValue(),
-            $worksheet->getCell('A1')->getCalculatedValue()
-        ));
+        $helper->log("$formula = " . $worksheet->getCell('A1')->getCalculatedValue());
     }
 }
diff --git a/samples/Calculations/Engineering/BESSELJ.php b/samples/Calculations/Engineering/BESSELJ.php
index 3aa4788682..6a3d9c8ca7 100644
--- a/samples/Calculations/Engineering/BESSELJ.php
+++ b/samples/Calculations/Engineering/BESSELJ.php
@@ -18,12 +18,9 @@
 for ($n = 0; $n <= 5; ++$n) {
     for ($x = 0; $x <= 5; $x = $x + 0.25) {
         Calculation::getInstance($spreadsheet)->flushInstance();
-        $worksheet->setCellValue('A1', "=BESSELJ({$x}, {$n})");
+        $formula = "BESSELJ({$x}, {$n})";
+        $worksheet->setCellValue('A1', "=$formula");
 
-        $helper->log(sprintf(
-            '%s = %f',
-            $worksheet->getCell('A1')->getValue(),
-            $worksheet->getCell('A1')->getCalculatedValue()
-        ));
+        $helper->log("$formula = " . $worksheet->getCell('A1')->getCalculatedValue());
     }
 }
diff --git a/samples/Calculations/Engineering/BESSELK.php b/samples/Calculations/Engineering/BESSELK.php
index ee8698e94a..e45e3de770 100644
--- a/samples/Calculations/Engineering/BESSELK.php
+++ b/samples/Calculations/Engineering/BESSELK.php
@@ -18,12 +18,9 @@
 for ($n = 0; $n <= 5; ++$n) {
     for ($x = 0; $x <= 5; $x = $x + 0.25) {
         Calculation::getInstance($spreadsheet)->flushInstance();
-        $worksheet->setCellValue('A1', "=BESSELK({$x}, {$n})");
+        $formula = "BESSELK({$x}, {$n})";
+        $worksheet->setCellValue('A1', "=$formula");
 
-        $helper->log(sprintf(
-            '%s = %f',
-            $worksheet->getCell('A1')->getValue(),
-            $worksheet->getCell('A1')->getCalculatedValue()
-        ));
+        $helper->log("$formula = " . $worksheet->getCell('A1')->getCalculatedValue());
     }
 }
diff --git a/samples/Calculations/Engineering/BESSELY.php b/samples/Calculations/Engineering/BESSELY.php
index 750b7204bc..7bf16d26eb 100644
--- a/samples/Calculations/Engineering/BESSELY.php
+++ b/samples/Calculations/Engineering/BESSELY.php
@@ -18,12 +18,9 @@
 for ($n = 0; $n <= 5; ++$n) {
     for ($x = 0; $x <= 5; $x = $x + 0.25) {
         Calculation::getInstance($spreadsheet)->flushInstance();
-        $worksheet->setCellValue('A1', "=BESSELY({$x}, {$n})");
+        $formula = "BESSELY({$x}, {$n})";
+        $worksheet->setCellValue('A1', "=$formula");
 
-        $helper->log(sprintf(
-            '%s = %f',
-            $worksheet->getCell('A1')->getValue(),
-            $worksheet->getCell('A1')->getCalculatedValue()
-        ));
+        $helper->log("$formula = " . $worksheet->getCell('A1')->getCalculatedValue());
     }
 }
diff --git a/samples/Calculations/Engineering/BIN2DEC.php b/samples/Calculations/Engineering/BIN2DEC.php
index 0c4c45324c..8f7865ee4d 100644
--- a/samples/Calculations/Engineering/BIN2DEC.php
+++ b/samples/Calculations/Engineering/BIN2DEC.php
@@ -37,10 +37,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Binary %s is decimal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Binary ' . $worksheet->getCell("A$row")->getValue()
+        . ' is decimal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/BIN2HEX.php b/samples/Calculations/Engineering/BIN2HEX.php
index 51a1119977..593999a211 100644
--- a/samples/Calculations/Engineering/BIN2HEX.php
+++ b/samples/Calculations/Engineering/BIN2HEX.php
@@ -37,10 +37,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Binary %s is hexadecimal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Binary ' . $worksheet->getCell("A$row")->getValue()
+        . ' is hexadecimal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/BIN2OCT.php b/samples/Calculations/Engineering/BIN2OCT.php
index c320d360a4..be01961092 100644
--- a/samples/Calculations/Engineering/BIN2OCT.php
+++ b/samples/Calculations/Engineering/BIN2OCT.php
@@ -37,10 +37,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Binary %s is octal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Binary ' . $worksheet->getCell("A$row")->getValue()
+        . ' is octal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/BITAND.php b/samples/Calculations/Engineering/BITAND.php
index 2a8f7a3cc5..b174045617 100644
--- a/samples/Calculations/Engineering/BITAND.php
+++ b/samples/Calculations/Engineering/BITAND.php
@@ -36,14 +36,19 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): Bitwise AND of %d (%s) and %d (%s) is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-        $worksheet->getCell('E' . $row)->getCalculatedValue(),
-        $worksheet->getCell('F' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): Bitwise AND of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+        . ') and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . '('
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ') is '
+        . $worksheet->getCell('E' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('F' . $row)->getCalculatedValue()
+        . ')'
+    );
 }
diff --git a/samples/Calculations/Engineering/BITLSHIFT.php b/samples/Calculations/Engineering/BITLSHIFT.php
index 872c8098db..57da865f9d 100644
--- a/samples/Calculations/Engineering/BITLSHIFT.php
+++ b/samples/Calculations/Engineering/BITLSHIFT.php
@@ -38,28 +38,37 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): Bitwise Left Shift of %d (%s) by 1 bit is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-    ));
-    $helper->log(sprintf(
-        '(E%d): Bitwise Left Shift of %d (%s) by 2 bits is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-        $worksheet->getCell('E' . $row)->getCalculatedValue(),
-        $worksheet->getCell('F' . $row)->getCalculatedValue(),
-    ));
-    $helper->log(sprintf(
-        '(E%d): Bitwise Left Shift of %d (%s) by 3 bits is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-        $worksheet->getCell('G' . $row)->getCalculatedValue(),
-        $worksheet->getCell('H' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): Bitwise Left Shift of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+        . ') by 1 bit is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ')'
+    );
+    $helper->log(
+        "(E$row): Bitwise Left Shift of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+        . ') by 2 bits is '
+        . $worksheet->getCell('E' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('F' . $row)->getCalculatedValue()
+        . ')'
+    );
+    $helper->log(
+        "(E$row): Bitwise Left Shift of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+        . ') by 3 bits is '
+        . $worksheet->getCell('G' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('H' . $row)->getCalculatedValue()
+        . ')'
+    );
 }
diff --git a/samples/Calculations/Engineering/BITOR.php b/samples/Calculations/Engineering/BITOR.php
index 1bf7f71d11..10469be2b7 100644
--- a/samples/Calculations/Engineering/BITOR.php
+++ b/samples/Calculations/Engineering/BITOR.php
@@ -36,14 +36,19 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): Bitwise OR of %d (%s) and %d (%s) is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-        $worksheet->getCell('E' . $row)->getCalculatedValue(),
-        $worksheet->getCell('F' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): Bitwise OR of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+        . ') and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . '('
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ') is '
+        . $worksheet->getCell('E' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('F' . $row)->getCalculatedValue()
+        . ')'
+    );
 }
diff --git a/samples/Calculations/Engineering/BITRSHIFT.php b/samples/Calculations/Engineering/BITRSHIFT.php
index 3e7f3a88d5..ac0415209b 100644
--- a/samples/Calculations/Engineering/BITRSHIFT.php
+++ b/samples/Calculations/Engineering/BITRSHIFT.php
@@ -36,28 +36,37 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): Bitwise Right Shift of %d (%s) by 1 bit is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-    ));
-    $helper->log(sprintf(
-        '(E%d): Bitwise Right Shift of %d (%s) by 2 bits is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-        $worksheet->getCell('E' . $row)->getCalculatedValue(),
-        $worksheet->getCell('F' . $row)->getCalculatedValue(),
-    ));
-    $helper->log(sprintf(
-        '(E%d): Bitwise Right Shift of %d (%s) by 3 bits is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-        $worksheet->getCell('G' . $row)->getCalculatedValue(),
-        $worksheet->getCell('H' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): Bitwise Right Shift of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+        . ') by 1 bit is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ')'
+    );
+    $helper->log(
+        "(E$row): Bitwise Right Shift of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+        . ') by 2 bits is '
+        . $worksheet->getCell('E' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('F' . $row)->getCalculatedValue()
+        . ')'
+    );
+    $helper->log(
+        "(E$row): Bitwise Right Shift of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+        . ') by 3 bits is '
+        . $worksheet->getCell('G' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('H' . $row)->getCalculatedValue()
+        . ')'
+    );
 }
diff --git a/samples/Calculations/Engineering/BITXOR.php b/samples/Calculations/Engineering/BITXOR.php
index 482662cd78..fa9f9ede4f 100644
--- a/samples/Calculations/Engineering/BITXOR.php
+++ b/samples/Calculations/Engineering/BITXOR.php
@@ -36,14 +36,19 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): Bitwise XOR of %d (%s) and %d (%s) is %d (%s)',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-        $worksheet->getCell('E' . $row)->getCalculatedValue(),
-        $worksheet->getCell('F' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): Bitwise XOR of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' ('
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+        . ') and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . '('
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ') is '
+        . $worksheet->getCell('E' . $row)->getCalculatedValue()
+        . ' ('
+        . $worksheet->getCell('F' . $row)->getCalculatedValue()
+        . ')'
+    );
 }
diff --git a/samples/Calculations/Engineering/COMPLEX.php b/samples/Calculations/Engineering/COMPLEX.php
index c58a179777..ff356cb5d1 100644
--- a/samples/Calculations/Engineering/COMPLEX.php
+++ b/samples/Calculations/Engineering/COMPLEX.php
@@ -32,10 +32,10 @@
 }
 
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(A%d): Formula %s result is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('A' . $row)->getCalculatedValue()
-    ));
+    $helper->log(
+        "(A$row): Formula "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' result is '
+        . $worksheet->getCell('A' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/CONVERT.php b/samples/Calculations/Engineering/CONVERT.php
index bce56ba507..7b8c889fef 100644
--- a/samples/Calculations/Engineering/CONVERT.php
+++ b/samples/Calculations/Engineering/CONVERT.php
@@ -16,43 +16,47 @@
 
 // Add some data
 $conversions = [
-    [1, '"lbm"', '"kg"'],
-    [1, '"gal"', '"l"'],
-    [24, '"in"', '"ft"'],
-    [100, '"yd"', '"m"'],
-    [500, '"mi"', '"km"'],
-    [7.5, '"min"', '"sec"'],
-    [5, '"F"', '"C"'],
-    [32, '"C"', '"K"'],
-    [100, '"m2"', '"ft2"'],
+    [1, 'lbm', 'kg'],
+    [1, 'gal', 'l'],
+    [24, 'in', 'ft'],
+    [100, 'yd', 'm'],
+    [500, 'mi', 'km'],
+    [7.5, 'min', 'sec'],
+    [5, 'F', 'C'],
+    [32, 'C', 'K'],
+    [100, 'm2', 'ft2'],
 ];
 $testDataCount = count($conversions);
 
 $worksheet->fromArray($conversions, null, 'A1');
 
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $worksheet->setCellValue('D' . $row, '=CONVERT(' . implode(',', $conversions[$row - 1]) . ')');
+    $data = $conversions[$row - 1];
+    $worksheet->setCellValue("D$row", "=CONVERT({$data[0]},\"{$data[1]}\",\"{$data[2]}\")");
 }
 
 $worksheet->setCellValue('H1', '=CONVERT(CONVERT(100,"m","ft"),"m","ft")');
 
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(A%d): Unit of Measure Conversion Formula %s - %d %s is %f %s',
-        $row,
-        $worksheet->getCell('D' . $row)->getValue(),
-        $worksheet->getCell('A' . $row)->getValue(),
-        trim($worksheet->getCell('B' . $row)->getValue(), '"'),
-        $worksheet->getCell('D' . $row)->getCalculatedValue(),
-        trim($worksheet->getCell('C' . $row)->getValue(), '"')
-    ));
+    $helper->log(
+        "(A$row): Unit of Measure Conversion Formula "
+        . $worksheet->getCell('D' . $row)->getValue()
+        . ' - '
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('D' . $row)->getCalculatedValue()
+        . ' '
+        . $worksheet->getCell('C' . $row)->getValue()
+    );
 }
 
 $helper->log('Old method for area conversions, before MS Excel introduced area Units of Measure');
 
-$helper->log(sprintf(
-    '(A%d): Unit of Measure Conversion Formula %s result is %s',
-    $row,
-    $worksheet->getCell('H1')->getValue(),
-    $worksheet->getCell('H1')->getCalculatedValue()
-));
+$helper->log(
+    "(A$row): Unit of Measure Conversion Formula "
+    . $worksheet->getCell('H1')->getValue()
+    . ' result is '
+    . $worksheet->getCell('H1')->getCalculatedValue()
+);
diff --git a/samples/Calculations/Engineering/DEC2BIN.php b/samples/Calculations/Engineering/DEC2BIN.php
index 2a064c0616..05bcb4289f 100644
--- a/samples/Calculations/Engineering/DEC2BIN.php
+++ b/samples/Calculations/Engineering/DEC2BIN.php
@@ -38,10 +38,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Decimal %s is binary %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Decimal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is binary ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/DEC2HEX.php b/samples/Calculations/Engineering/DEC2HEX.php
index 0a19ae544d..9c0368887a 100644
--- a/samples/Calculations/Engineering/DEC2HEX.php
+++ b/samples/Calculations/Engineering/DEC2HEX.php
@@ -39,10 +39,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Decimal %s is hexadecimal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Decimal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is hexadecimal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/DEC2OCT.php b/samples/Calculations/Engineering/DEC2OCT.php
index fc11a832bb..f8b467e913 100644
--- a/samples/Calculations/Engineering/DEC2OCT.php
+++ b/samples/Calculations/Engineering/DEC2OCT.php
@@ -39,10 +39,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Decimal %s is octal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Decimal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is octal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/DELTA.php b/samples/Calculations/Engineering/DELTA.php
index cd51b16165..3e1138b1b4 100644
--- a/samples/Calculations/Engineering/DELTA.php
+++ b/samples/Calculations/Engineering/DELTA.php
@@ -35,12 +35,14 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): Compare values %d and %d - Result is %d - %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-        $comparison[$worksheet->getCell('C' . $row)->getCalculatedValue()]
-    ));
+    $helper->log(
+        "(E$row): Compare values "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' - Result is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+        . ' - '
+        . $comparison[$worksheet->getCell('C' . $row)->getCalculatedValue()]
+    );
 }
diff --git a/samples/Calculations/Engineering/ERF.php b/samples/Calculations/Engineering/ERF.php
index e650588893..c555129e5b 100644
--- a/samples/Calculations/Engineering/ERF.php
+++ b/samples/Calculations/Engineering/ERF.php
@@ -45,23 +45,26 @@
 // Test the formulae
 $helper->log('ERF() With a single argument');
 for ($row = 1; $row <= $testDataCount1; ++$row) {
-    $helper->log(sprintf(
-        '(C%d): %s The error function integrated between 0 and %f is %f',
-        $row,
-        $worksheet->getCell('C' . $row)->getValue(),
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(C$row): "
+        . $worksheet->getCell('C' . $row)->getValue()
+        . ' The error function integrated between 0 and '
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
 
 $helper->log('ERF() With two arguments');
 for ($row = $testDataCount1 + 1; $row <= $testDataCount2 + $testDataCount1; ++$row) {
-    $helper->log(sprintf(
-        '(C%d): %s The error function integrated between %f and %f is %f',
-        $row,
-        $worksheet->getCell('C' . $row)->getValue(),
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(C$row): "
+        . $worksheet->getCell('C' . $row)->getValue()
+        . ' The error function integrated between '
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/ERFC.php b/samples/Calculations/Engineering/ERFC.php
index 5e7bcc6d08..bfb038fea9 100644
--- a/samples/Calculations/Engineering/ERFC.php
+++ b/samples/Calculations/Engineering/ERFC.php
@@ -31,11 +31,12 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): %s The complementary error function integrated by %f and infinity is %f',
-        $row,
-        $worksheet->getCell('C' . $row)->getValue(),
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): "
+        . $worksheet->getCell('C' . $row)->getValue()
+        . ' The complementary error function integrated by '
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and infinity is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/GESTEP.php b/samples/Calculations/Engineering/GESTEP.php
index 73f0a31cea..fad70fe48a 100644
--- a/samples/Calculations/Engineering/GESTEP.php
+++ b/samples/Calculations/Engineering/GESTEP.php
@@ -38,16 +38,22 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
+    /** @var int */
+    $aValue = $worksheet->getCell('A' . $row)->getValue();
+    /** @var int */
+    $bValue = $worksheet->getCell('B' . $row)->getValue();
+    /** @var int */
+    $cValue = $worksheet->getCell('C' . $row)->getCalculatedValue();
     $helper->log(sprintf(
         '(E%d): Compare value %d and step %d - Result is %d - %s',
         $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
+        $aValue,
+        $bValue,
+        $cValue,
         sprintf(
-            $comparison[$worksheet->getCell('C' . $row)->getCalculatedValue()],
-            $worksheet->getCell('A' . $row)->getValue(),
-            $worksheet->getCell('B' . $row)->getValue(),
+            $comparison[$cValue],
+            $aValue,
+            $bValue,
         )
     ));
 }
diff --git a/samples/Calculations/Engineering/HEX2BIN.php b/samples/Calculations/Engineering/HEX2BIN.php
index 2ad0892565..629bdd0235 100644
--- a/samples/Calculations/Engineering/HEX2BIN.php
+++ b/samples/Calculations/Engineering/HEX2BIN.php
@@ -37,10 +37,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Hexadecimal %s is binary %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Hexadecimal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is binary ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/HEX2DEC.php b/samples/Calculations/Engineering/HEX2DEC.php
index 745d411054..cb9ec0f496 100644
--- a/samples/Calculations/Engineering/HEX2DEC.php
+++ b/samples/Calculations/Engineering/HEX2DEC.php
@@ -39,10 +39,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Hexadecimal %s is decimal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Hexadecimal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is decimal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/HEX2OCT.php b/samples/Calculations/Engineering/HEX2OCT.php
index 3608c1bb3e..86b45675f5 100644
--- a/samples/Calculations/Engineering/HEX2OCT.php
+++ b/samples/Calculations/Engineering/HEX2OCT.php
@@ -37,10 +37,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Hexadecimal %s is octal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Hexadecimal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is octal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMABS.php b/samples/Calculations/Engineering/IMABS.php
index 9c6b843cde..8792472223 100644
--- a/samples/Calculations/Engineering/IMABS.php
+++ b/samples/Calculations/Engineering/IMABS.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The absolute value of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The absolute value of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMAGINARY.php b/samples/Calculations/Engineering/IMAGINARY.php
index 9913893855..357d84f0c8 100644
--- a/samples/Calculations/Engineering/IMAGINARY.php
+++ b/samples/Calculations/Engineering/IMAGINARY.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The imaginary component of %s is %f',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The imaginary component of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMARGUMENT.php b/samples/Calculations/Engineering/IMARGUMENT.php
index e559e95133..729e96a599 100644
--- a/samples/Calculations/Engineering/IMARGUMENT.php
+++ b/samples/Calculations/Engineering/IMARGUMENT.php
@@ -39,10 +39,11 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Theta Argument of %s is %f radians',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Theta Argument of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+        . ' radians'
+    );
 }
diff --git a/samples/Calculations/Engineering/IMCONJUGATE.php b/samples/Calculations/Engineering/IMCONJUGATE.php
index 3b4429ed06..49e506bdb8 100644
--- a/samples/Calculations/Engineering/IMCONJUGATE.php
+++ b/samples/Calculations/Engineering/IMCONJUGATE.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Conjugate of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Conjugate value of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMCOS.php b/samples/Calculations/Engineering/IMCOS.php
index 5b8f81ea3c..7b2f756af3 100644
--- a/samples/Calculations/Engineering/IMCOS.php
+++ b/samples/Calculations/Engineering/IMCOS.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Cosine of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Cosine of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMCOSH.php b/samples/Calculations/Engineering/IMCOSH.php
index 9a39376642..18517cda2c 100644
--- a/samples/Calculations/Engineering/IMCOSH.php
+++ b/samples/Calculations/Engineering/IMCOSH.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Hyperbolic Cosine of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Hyperbolic Cosine of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMCOT.php b/samples/Calculations/Engineering/IMCOT.php
index e3d980cd20..cfb48e0370 100644
--- a/samples/Calculations/Engineering/IMCOT.php
+++ b/samples/Calculations/Engineering/IMCOT.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Cotangent of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Cotangent of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMCSC.php b/samples/Calculations/Engineering/IMCSC.php
index ab6695d06c..2168ea2d71 100644
--- a/samples/Calculations/Engineering/IMCSC.php
+++ b/samples/Calculations/Engineering/IMCSC.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Cosecant of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Cosecant of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMCSCH.php b/samples/Calculations/Engineering/IMCSCH.php
index 4513d9e94e..dcee949c15 100644
--- a/samples/Calculations/Engineering/IMCSCH.php
+++ b/samples/Calculations/Engineering/IMCSCH.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Hyperbolic Cosecant of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Hyperbolic Cosecant of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMDIV.php b/samples/Calculations/Engineering/IMDIV.php
index 9512be573c..1ef348692a 100644
--- a/samples/Calculations/Engineering/IMDIV.php
+++ b/samples/Calculations/Engineering/IMDIV.php
@@ -32,11 +32,12 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Quotient of %s and %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Quotient of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMEXP.php b/samples/Calculations/Engineering/IMEXP.php
index 7f5837b239..aa96033d38 100644
--- a/samples/Calculations/Engineering/IMEXP.php
+++ b/samples/Calculations/Engineering/IMEXP.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Exponential of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Exponential of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMLN.php b/samples/Calculations/Engineering/IMLN.php
index 956182573a..f6422bb9cd 100644
--- a/samples/Calculations/Engineering/IMLN.php
+++ b/samples/Calculations/Engineering/IMLN.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Natural Logarithm of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Natural Logarithm of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMLOG10.php b/samples/Calculations/Engineering/IMLOG10.php
index d501c3deda..586fa1b2ea 100644
--- a/samples/Calculations/Engineering/IMLOG10.php
+++ b/samples/Calculations/Engineering/IMLOG10.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Base-10 Logarithm of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Base-10 Logarithm of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMLOG2.php b/samples/Calculations/Engineering/IMLOG2.php
index 25986b3986..3fb362e892 100644
--- a/samples/Calculations/Engineering/IMLOG2.php
+++ b/samples/Calculations/Engineering/IMLOG2.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Base-2 Logarithm of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Base-2 Logarithm of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMPOWER.php b/samples/Calculations/Engineering/IMPOWER.php
index c6674fbe95..d040e3089b 100644
--- a/samples/Calculations/Engineering/IMPOWER.php
+++ b/samples/Calculations/Engineering/IMPOWER.php
@@ -39,11 +39,12 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): %s raised to the power of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' raised to the power of '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMPRODUCT.php b/samples/Calculations/Engineering/IMPRODUCT.php
index f81bc66684..f21022f8d8 100644
--- a/samples/Calculations/Engineering/IMPRODUCT.php
+++ b/samples/Calculations/Engineering/IMPRODUCT.php
@@ -32,11 +32,12 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Product of %s and %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Product of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMREAL.php b/samples/Calculations/Engineering/IMREAL.php
index 4e537c0fd7..708a49c4e0 100644
--- a/samples/Calculations/Engineering/IMREAL.php
+++ b/samples/Calculations/Engineering/IMREAL.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The real component of %s is %f radians',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The real component of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMSEC.php b/samples/Calculations/Engineering/IMSEC.php
index e6c524b3ca..d150bbfb07 100644
--- a/samples/Calculations/Engineering/IMSEC.php
+++ b/samples/Calculations/Engineering/IMSEC.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Secant of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Secant of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMSECH.php b/samples/Calculations/Engineering/IMSECH.php
index e07b6e08e4..bced466490 100644
--- a/samples/Calculations/Engineering/IMSECH.php
+++ b/samples/Calculations/Engineering/IMSECH.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Hyperbolic Secant of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Hyperbolic Ssecant of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMSIN.php b/samples/Calculations/Engineering/IMSIN.php
index d3b8c281d9..8786461c0f 100644
--- a/samples/Calculations/Engineering/IMSIN.php
+++ b/samples/Calculations/Engineering/IMSIN.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Sine of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Sine of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMSINH.php b/samples/Calculations/Engineering/IMSINH.php
index ac0a9039be..73b8ea48c7 100644
--- a/samples/Calculations/Engineering/IMSINH.php
+++ b/samples/Calculations/Engineering/IMSINH.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Hyperbolic Sine of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Hyperbolic Sine of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMSQRT.php b/samples/Calculations/Engineering/IMSQRT.php
index c2573c9197..1475836da0 100644
--- a/samples/Calculations/Engineering/IMSQRT.php
+++ b/samples/Calculations/Engineering/IMSQRT.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Square Root of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Square Root of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMSUB.php b/samples/Calculations/Engineering/IMSUB.php
index 90bd27a4f0..a777bfde8f 100644
--- a/samples/Calculations/Engineering/IMSUB.php
+++ b/samples/Calculations/Engineering/IMSUB.php
@@ -32,11 +32,12 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Difference between %s and %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Difference between "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMSUM.php b/samples/Calculations/Engineering/IMSUM.php
index 2a8be32070..464c3d2c2b 100644
--- a/samples/Calculations/Engineering/IMSUM.php
+++ b/samples/Calculations/Engineering/IMSUM.php
@@ -32,11 +32,12 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Sum of %s and %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getValue(),
-        $worksheet->getCell('C' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Sum of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/IMTAN.php b/samples/Calculations/Engineering/IMTAN.php
index ffaa53b246..492c332934 100644
--- a/samples/Calculations/Engineering/IMTAN.php
+++ b/samples/Calculations/Engineering/IMTAN.php
@@ -39,10 +39,10 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(E%d): The Tangent of %s is %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(E$row): The Tangent of "
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('B' . $row)->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/OCT2BIN.php b/samples/Calculations/Engineering/OCT2BIN.php
index 9c4bbf863d..7a2115bca4 100644
--- a/samples/Calculations/Engineering/OCT2BIN.php
+++ b/samples/Calculations/Engineering/OCT2BIN.php
@@ -38,10 +38,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Octal %s is binary %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Octal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is binary ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/OCT2DEC.php b/samples/Calculations/Engineering/OCT2DEC.php
index ea6afb2fb7..c472523e41 100644
--- a/samples/Calculations/Engineering/OCT2DEC.php
+++ b/samples/Calculations/Engineering/OCT2DEC.php
@@ -40,10 +40,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Octal %s is decimal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Octal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is decimal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/Engineering/OCT2HEX.php b/samples/Calculations/Engineering/OCT2HEX.php
index 47e9b6e16d..8a55543e60 100644
--- a/samples/Calculations/Engineering/OCT2HEX.php
+++ b/samples/Calculations/Engineering/OCT2HEX.php
@@ -40,10 +40,9 @@
 
 // Test the formulae
 for ($row = 1; $row <= $testDataCount; ++$row) {
-    $helper->log(sprintf(
-        '(B%d): Octal %s is hexadecimal %s',
-        $row,
-        $worksheet->getCell('A' . $row)->getValue(),
-        $worksheet->getCell('B' . $row)->getCalculatedValue(),
-    ));
+    $helper->log(
+        "(B$row): "
+        . 'Octal ' . $worksheet->getCell("A$row")->getValue()
+        . ' is hexadecimal ' . $worksheet->getCell("B$row")->getCalculatedValue()
+    );
 }
diff --git a/samples/Calculations/LookupRef/ADDRESS.php b/samples/Calculations/LookupRef/ADDRESS.php
index 9e01ddb5f3..7975063fb3 100644
--- a/samples/Calculations/LookupRef/ADDRESS.php
+++ b/samples/Calculations/LookupRef/ADDRESS.php
@@ -18,5 +18,5 @@
 
 for ($row = 1; $row <= 5; ++$row) {
     $cell = $worksheet->getCell("A{$row}");
-    $helper->log("A{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("A{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
diff --git a/samples/Calculations/LookupRef/COLUMN.php b/samples/Calculations/LookupRef/COLUMN.php
index e9e5846608..45b591ba2c 100644
--- a/samples/Calculations/LookupRef/COLUMN.php
+++ b/samples/Calculations/LookupRef/COLUMN.php
@@ -16,8 +16,8 @@
 
 for ($row = 1; $row <= 2; ++$row) {
     $cell = $worksheet->getCell("A{$row}");
-    $helper->log("A{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("A{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
 
 $cell = $worksheet->getCell('F1');
-$helper->log("F1: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+$helper->log('F1: ' . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
diff --git a/samples/Calculations/LookupRef/COLUMNS.php b/samples/Calculations/LookupRef/COLUMNS.php
index 4d7f8d10e6..b3e81fe0d7 100644
--- a/samples/Calculations/LookupRef/COLUMNS.php
+++ b/samples/Calculations/LookupRef/COLUMNS.php
@@ -17,5 +17,5 @@
 
 for ($row = 1; $row <= 4; ++$row) {
     $cell = $worksheet->getCell("A{$row}");
-    $helper->log("A{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("A{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
diff --git a/samples/Calculations/LookupRef/INDEX.php b/samples/Calculations/LookupRef/INDEX.php
index 9ef0b94562..e0a734518b 100644
--- a/samples/Calculations/LookupRef/INDEX.php
+++ b/samples/Calculations/LookupRef/INDEX.php
@@ -35,5 +35,5 @@
 
 for ($row = 11; $row <= 16; ++$row) {
     $cell = $worksheet->getCell("A{$row}");
-    $helper->log("A{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("A{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
diff --git a/samples/Calculations/LookupRef/INDIRECT.php b/samples/Calculations/LookupRef/INDIRECT.php
index ffbada9ad7..acfd5dd22c 100644
--- a/samples/Calculations/LookupRef/INDIRECT.php
+++ b/samples/Calculations/LookupRef/INDIRECT.php
@@ -29,5 +29,5 @@
 
 for ($row = 1; $row <= 5; ++$row) {
     $cell = $worksheet->getCell("A{$row}");
-    $helper->log("A{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("A{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
diff --git a/samples/Calculations/LookupRef/OFFSET.php b/samples/Calculations/LookupRef/OFFSET.php
index ae613ec525..1757353358 100644
--- a/samples/Calculations/LookupRef/OFFSET.php
+++ b/samples/Calculations/LookupRef/OFFSET.php
@@ -29,5 +29,5 @@
 
 for ($row = 1; $row <= 4; ++$row) {
     $cell = $worksheet->getCell("H{$row}");
-    $helper->log("H{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("H{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
diff --git a/samples/Calculations/LookupRef/ROW.php b/samples/Calculations/LookupRef/ROW.php
index 560639a516..fc7a500f0e 100644
--- a/samples/Calculations/LookupRef/ROW.php
+++ b/samples/Calculations/LookupRef/ROW.php
@@ -16,5 +16,5 @@
 
 for ($row = 1; $row <= 3; ++$row) {
     $cell = $worksheet->getCell("A{$row}");
-    $helper->log("A{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("A{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
diff --git a/samples/Calculations/LookupRef/ROWS.php b/samples/Calculations/LookupRef/ROWS.php
index 3cdf085bd9..6d1be29f4e 100644
--- a/samples/Calculations/LookupRef/ROWS.php
+++ b/samples/Calculations/LookupRef/ROWS.php
@@ -16,5 +16,5 @@
 
 for ($row = 1; $row <= 3; ++$row) {
     $cell = $worksheet->getCell("A{$row}");
-    $helper->log("A{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+    $helper->log("A{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
 }
diff --git a/samples/Calculations/LookupRef/VLOOKUP.php b/samples/Calculations/LookupRef/VLOOKUP.php
index 16a911e86e..352790a7c7 100644
--- a/samples/Calculations/LookupRef/VLOOKUP.php
+++ b/samples/Calculations/LookupRef/VLOOKUP.php
@@ -43,6 +43,6 @@
 for ($column = 'H'; $column !== 'K'; ++$column) {
     for ($row = 4; $row <= 5; ++$row) {
         $cell = $worksheet->getCell("{$column}{$row}");
-        $helper->log("{$column}{$row}: {$cell->getValue()} => {$cell->getCalculatedValue()}");
+        $helper->log("{$column}{$row}: " . $cell->getValue() . ' => ' . $cell->getCalculatedValue());
     }
 }
diff --git a/samples/Chart/33_Chart_create_line_dateaxis.php b/samples/Chart/33_Chart_create_line_dateaxis.php
index f93b83042f..00eacbd0e1 100644
--- a/samples/Chart/33_Chart_create_line_dateaxis.php
+++ b/samples/Chart/33_Chart_create_line_dateaxis.php
@@ -343,6 +343,7 @@ function dateRange(int $nrows, Spreadsheet $wrkbk): array
     $dataSheet = $wrkbk->getSheetByNameOrThrow('Data');
 
     // start the xaxis at the beginning of the quarter of the first date
+    /** @var string */
     $startDateStr = $dataSheet->getCell('B2')->getValue(); // yyyy-mm-dd date string
     $startDate = DateTime::createFromFormat('Y-m-d', $startDateStr); // php date obj
     if ($startDate === false) {
@@ -358,6 +359,7 @@ function dateRange(int $nrows, Spreadsheet $wrkbk): array
     $ExcelQtrStartDateVal = SharedDate::convertIsoDate($qtrStartStr);
 
     // end the xaxis at the end of the quarter of the last date
+    /** @var string */
     $lastDateStr = $dataSheet->getCell([2, $nrows + 1])->getValue();
     $lastDate = DateTime::createFromFormat('Y-m-d', $lastDateStr);
     if ($lastDate === false) {
diff --git a/samples/ConditionalFormatting/05_Date_Comparisons.php b/samples/ConditionalFormatting/05_Date_Comparisons.php
index 0834939d3b..9384a826c4 100644
--- a/samples/ConditionalFormatting/05_Date_Comparisons.php
+++ b/samples/ConditionalFormatting/05_Date_Comparisons.php
@@ -122,7 +122,9 @@
     $dateWizard = $wizardFactory->newRule(Wizard::DATES_OCCURRING);
     $conditionalStyles = [];
 
-    $methodName = trim($spreadsheet->getActiveSheet()->getCell("{$column}1")->getValue(), '()');
+    /** @var string */
+    $cellContents = $spreadsheet->getActiveSheet()->getCell("{$column}1")->getValue();
+    $methodName = trim($cellContents, '()');
     $dateWizard->$methodName()
         ->setStyle($yellowStyle);
 
diff --git a/samples/DefinedNames/AbsoluteNamedRange.php b/samples/DefinedNames/AbsoluteNamedRange.php
index 30afc00d65..4b27799b30 100644
--- a/samples/DefinedNames/AbsoluteNamedRange.php
+++ b/samples/DefinedNames/AbsoluteNamedRange.php
@@ -44,11 +44,17 @@
     ->setCellValue("B{$row}", "=SUM(B{$startRow}:B{$endRow})")
     ->setCellValue("C{$row}", "=SUM(C{$startRow}:C{$endRow})");
 
+/** @var float */
+$calc1 = $worksheet->getCell("B{$row}")->getCalculatedValue();
+/** @var float */
+$value = $worksheet->getCell('B1')->getValue();
+/** @var float */
+$calc2 = $worksheet->getCell("C{$row}")->getCalculatedValue();
 $helper->log(sprintf(
     'Worked %.2f hours at a rate of %.2f - Charge to the client is %.2f',
-    $worksheet->getCell("B{$row}")->getCalculatedValue(),
-    $worksheet->getCell('B1')->getValue(),
-    $worksheet->getCell("C{$row}")->getCalculatedValue()
+    $calc1,
+    $value,
+    $calc2
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/DefinedNames/NamedFormulaeAndRanges.php b/samples/DefinedNames/NamedFormulaeAndRanges.php
index a5ca80e706..8d9dd75a5e 100644
--- a/samples/DefinedNames/NamedFormulaeAndRanges.php
+++ b/samples/DefinedNames/NamedFormulaeAndRanges.php
@@ -55,11 +55,17 @@
     ->setCellValue("B{$row}", '=COLUMN_TOTALS')
     ->setCellValue("C{$row}", '=COLUMN_TOTALS');
 
+/** @var float */
+$calc1 = $worksheet->getCell("B{$row}")->getCalculatedValue();
+/** @var float */
+$value = $worksheet->getCell('B1')->getValue();
+/** @var float */
+$calc2 = $worksheet->getCell("C{$row}")->getCalculatedValue();
 $helper->log(sprintf(
     'Worked %.2f hours at a rate of %.2f - Charge to the client is %.2f',
-    $worksheet->getCell("B{$row}")->getCalculatedValue(),
-    $worksheet->getCell('B1')->getValue(),
-    $worksheet->getCell("C{$row}")->getCalculatedValue()
+    $calc1,
+    $value,
+    $calc2
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/DefinedNames/RelativeNamedRange.php b/samples/DefinedNames/RelativeNamedRange.php
index fac75a4715..99de212cf8 100644
--- a/samples/DefinedNames/RelativeNamedRange.php
+++ b/samples/DefinedNames/RelativeNamedRange.php
@@ -47,11 +47,17 @@
     ->setCellValue("B{$row}", "=SUM(B{$startRow}:B{$endRow})")
     ->setCellValue("C{$row}", "=SUM(C{$startRow}:C{$endRow})");
 
+/** @var float */
+$calc1 = $worksheet->getCell("B{$row}")->getCalculatedValue();
+/** @var float */
+$value = $worksheet->getCell('B1')->getValue();
+/** @var float */
+$calc2 = $worksheet->getCell("C{$row}")->getCalculatedValue();
 $helper->log(sprintf(
     'Worked %.2f hours at a rate of %.2f - Charge to the client is %.2f',
-    $worksheet->getCell("B{$row}")->getCalculatedValue(),
-    $worksheet->getCell('B1')->getValue(),
-    $worksheet->getCell("C{$row}")->getCalculatedValue()
+    $calc1,
+    $value,
+    $calc2
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/DefinedNames/RelativeNamedRange2.php b/samples/DefinedNames/RelativeNamedRange2.php
index b3e957fd2e..0814e0aa6b 100644
--- a/samples/DefinedNames/RelativeNamedRange2.php
+++ b/samples/DefinedNames/RelativeNamedRange2.php
@@ -50,11 +50,17 @@
     ->setCellValue("B{$row}", '=SUM(COLUMN_DATA_VALUES)')
     ->setCellValue("C{$row}", '=SUM(COLUMN_DATA_VALUES)');
 
+/** @var float */
+$calc1 = $worksheet->getCell("B{$row}")->getCalculatedValue();
+/** @var float */
+$value = $worksheet->getCell('B1')->getValue();
+/** @var float */
+$calc2 = $worksheet->getCell("C{$row}")->getCalculatedValue();
 $helper->log(sprintf(
     'Worked %.2f hours at a rate of %.2f - Charge to the client is %.2f',
-    $worksheet->getCell("B{$row}")->getCalculatedValue(),
-    $worksheet->getCell('B1')->getValue(),
-    $worksheet->getCell("C{$row}")->getCalculatedValue()
+    $calc1,
+    $value,
+    $calc2
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/DefinedNames/RelativeNamedRangeAsFunction.php b/samples/DefinedNames/RelativeNamedRangeAsFunction.php
index 333d01ab0b..ebc85aafef 100644
--- a/samples/DefinedNames/RelativeNamedRangeAsFunction.php
+++ b/samples/DefinedNames/RelativeNamedRangeAsFunction.php
@@ -53,11 +53,17 @@
     ->setCellValue("B{$row}", '=SUM(COLUMN_DATA_VALUES)')
     ->setCellValue("C{$row}", '=SUM(COLUMN_DATA_VALUES)');
 
+/** @var float */
+$calc1 = $worksheet->getCell("B{$row}")->getCalculatedValue();
+/** @var float */
+$value = $worksheet->getCell('B1')->getValue();
+/** @var float */
+$calc2 = $worksheet->getCell("C{$row}")->getCalculatedValue();
 $helper->log(sprintf(
     'Worked %.2f hours at a rate of %.2f - Charge to the client is %.2f',
-    $worksheet->getCell("B{$row}")->getCalculatedValue(),
-    $worksheet->getCell('B1')->getValue(),
-    $worksheet->getCell("C{$row}")->getCalculatedValue()
+    $calc1,
+    $value,
+    $calc2
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/DefinedNames/ScopedNamedRange.php b/samples/DefinedNames/ScopedNamedRange.php
index 88bc62777e..dc6a211faa 100644
--- a/samples/DefinedNames/ScopedNamedRange.php
+++ b/samples/DefinedNames/ScopedNamedRange.php
@@ -64,15 +64,20 @@
 if ($range === null || $range->getWorksheet() === null) {
     throw new Exception('expected named range not found');
 }
+/** @var float */
 $chargeRateCellValue = $spreadsheet
     ->getSheetByNameOrThrow($range->getWorksheet()->getTitle())
     ->getCell($range->getCellsInRange()[0])->getValue();
 
+/** @var float */
+$calc1 = $worksheet->getCell("B{$row}")->getCalculatedValue();
+/** @var float */
+$calc2 = $worksheet->getCell("C{$row}")->getCalculatedValue();
 $helper->log(sprintf(
-    'Worked %.2f hours at a rate of %s - Charge to the client is %.2f',
-    $worksheet->getCell("B{$row}")->getCalculatedValue(),
+    'Worked %.2f hours at a rate of %.2f - Charge to the client is %.2f',
+    $calc1,
     $chargeRateCellValue,
-    $worksheet->getCell("C{$row}")->getCalculatedValue()
+    $calc2
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/DefinedNames/ScopedNamedRange2.php b/samples/DefinedNames/ScopedNamedRange2.php
index 5f0898c91e..9db8d44ea1 100644
--- a/samples/DefinedNames/ScopedNamedRange2.php
+++ b/samples/DefinedNames/ScopedNamedRange2.php
@@ -76,12 +76,18 @@
     ->setCellValue('B1', 4.5);
 
 foreach ($spreadsheet->getAllSheets() as $worksheet) {
+    /** @var float */
+    $calc1 = $worksheet->getCell("B{$row}")->getCalculatedValue();
+    /** @var float */
+    $value = $worksheet->getCell('B1')->getValue();
+    /** @var float */
+    $calc2 = $worksheet->getCell("C{$row}")->getCalculatedValue();
     $helper->log(sprintf(
         'Worked %.2f hours for "%s" at a rate of %.2f - Charge to the client is %.2f',
-        $worksheet->getCell("B{$row}")->getCalculatedValue(),
+        $calc1,
         $worksheet->getTitle(),
-        $worksheet->getCell('B1')->getValue(),
-        $worksheet->getCell("C{$row}")->getCalculatedValue()
+        $value,
+        $calc2
     ));
 }
 $worksheet = $spreadsheet->setActiveSheetIndex(0);
diff --git a/samples/DefinedNames/SimpleNamedFormula.php b/samples/DefinedNames/SimpleNamedFormula.php
index ea1f802da1..f0018100e1 100644
--- a/samples/DefinedNames/SimpleNamedFormula.php
+++ b/samples/DefinedNames/SimpleNamedFormula.php
@@ -32,12 +32,20 @@
     ->setCellValue('B4', '=TAX')
     ->setCellValue('B5', '=PRICE+TAX');
 
+/** @var float */
+$calc1 = $worksheet->getCell('B1')->getCalculatedValue();
+/** @var float */
+$value = $worksheet->getCell('B3')->getValue();
+/** @var float */
+$calc2 = $worksheet->getCell('B4')->getCalculatedValue();
+/** @var float */
+$calc3 = $worksheet->getCell('B5')->getCalculatedValue();
 $helper->log(sprintf(
     'With a Tax Rate of %.2f and a net price of %.2f, Tax is %.2f and the gross price is %.2f',
-    $worksheet->getCell('B1')->getCalculatedValue(),
-    $worksheet->getCell('B3')->getValue(),
-    $worksheet->getCell('B4')->getCalculatedValue(),
-    $worksheet->getCell('B5')->getCalculatedValue()
+    $calc1,
+    $value,
+    $calc2,
+    $calc3
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/DefinedNames/SimpleNamedRange.php b/samples/DefinedNames/SimpleNamedRange.php
index 7a7cdc94a1..12c0860165 100644
--- a/samples/DefinedNames/SimpleNamedRange.php
+++ b/samples/DefinedNames/SimpleNamedRange.php
@@ -26,12 +26,20 @@
     ->setCellValue('B4', '=PRICE*TAX_RATE')
     ->setCellValue('B5', '=PRICE*(1+TAX_RATE)');
 
+/** @var float */
+$calc1 = $worksheet->getCell('B1')->getCalculatedValue();
+/** @var float */
+$value = $worksheet->getCell('B3')->getValue();
+/** @var float */
+$calc2 = $worksheet->getCell('B4')->getCalculatedValue();
+/** @var float */
+$calc3 = $worksheet->getCell('B5')->getCalculatedValue();
 $helper->log(sprintf(
     'With a Tax Rate of %.2f and a net price of %.2f, Tax is %.2f and the gross price is %.2f',
-    $worksheet->getCell('B1')->getCalculatedValue(),
-    $worksheet->getCell('B3')->getValue(),
-    $worksheet->getCell('B4')->getCalculatedValue(),
-    $worksheet->getCell('B5')->getCalculatedValue()
+    $calc1,
+    $value,
+    $calc2,
+    $calc3
 ));
 
 $helper->write($spreadsheet, __FILE__, ['Xlsx']);
diff --git a/samples/Reading_workbook_data/Custom_properties.php b/samples/Reading_workbook_data/Custom_properties.php
index 1c222b5005..26f7c33d06 100644
--- a/samples/Reading_workbook_data/Custom_properties.php
+++ b/samples/Reading_workbook_data/Custom_properties.php
@@ -38,7 +38,7 @@
 
             break;
         case 'd':    // date
-            $propertyValue = date('l, d<\s\up>S</\s\up> F Y g:i A', $propertyValue);
+            $propertyValue = is_numeric($propertyValue) ? date('l, d<\s\u\p>S</\s\u\p> F Y g:i A', (int) $propertyValue) : '*****INVALID*****';
             $propertyType = 'date';
 
             break;