title: Making a simple calculator in html
body: <p>The problem is that I want the operation to be performed in a single input box as it usually is in calculators. The first value is stored in a variable then the operator button is pressed for the second value to be entered , the equal button has to perform the operation with the second value but I am unable to get the calculated answer it simply does not add it to the second value.</p>
  
  <pre><code>&lt;tr&gt;
      &lt;td&gt;&lt;input type=button value="+" OnClick="num1=calc.display.value;calc.display.value=' ';"&gt;&lt;/td&gt;
      &lt;td&gt;&lt;input type=button value="C" OnClick="calc.display.value='0'"&gt;&lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
      &lt;td&gt;&lt;input type=button value="=" OnClick="calc.display.value=calc.display.value+num1"&gt;&lt;/td&gt;
  &lt;/tr&gt;
  </code></pre>