You can perform basic calculation Arithmatic operation like i.e. +,-,*,/,% .But here % not give you reminder it divite the reslt by 100 which is percentage.
You see what haven't included or its range of output just change remove the display property from css file in class info
i.e.
.info{
display: none;// remove this line form css file
}
i.e.
<div class="info">
<h1><strong>NOTE:- This calculator does not cover all logic as the original basic calculator. </strong></h1>
<div class="about">
<h2><i class="fas fa-bug"></i> Bugs</h2>
<ol>
<li>Input data can not be deleted form the history Event if the output is empty.</li>
<li>'%' work as percentage finder but it just give the output divide by 100. <br><em>i.e.</em> 4 % = 0.04</li>
<li>You can make decimal no using Equal to operator(=) <br><em>i.e.</em> 2. operator(=) 4 give 2.4 which is decimal no.</li>
</ol>
</div>