Simple Calculator

Features:

• User inputs two numbers and selects an operation (+ - * /).
• PHP processes and returns the result.

<form method="post">
  <input type="number" name="num1" required>
  <input type="number" name="num2" required>
  <select name="operation">
&lt;option value="add"&gt;+&lt;/option&gt;
&lt;option value="sub"&gt;-&lt;/option&gt;
&lt;option value="mul"&gt;*&lt;/option&gt;
&lt;option value="div"&gt;/&lt;/option&gt;
  </select>
  <input type="submit" name="calculate" value="Calculate">
</form>

<?php
if(isset($_POST['calculate'])) {
  $num1 = $_POST['num1'];
  $num2 = $_POST['num2'];
  switch($_POST['operation']) {
case "add": echo $num1 + $num2; break;
case "sub": echo $num1 - $num2; break;
case "mul": echo $num1 * $num2; break;
case "div": echo $num1 / $num2; break;
  }
}
?>