ahref

<html>
<head>
  <title>Moo's Calculator</title>
</head>
<body>
  <form action="process.php" method="post">
    <input name="number1" type="number" /> 
    <select name="operation">
      <option>+</option>
       <option>-</option>
       <option>*</option>
       <option>/</option>
    </select>
    <input name="number2" type="number" />
    <input type="submit" />
  </form>
</body>
</html>
---------------------------------------------------
<html>
<head></head>
<body>

<?php

$number1 = $_POST['number1'];
$operation = $_POST['operation'];
$number2 = $_POST['number2'];
switch($operation)
        {
             case "+" : $total= $number1 + $number2; break;
             case "-" : $total= $number1 - $number2; break;
             case "*" : $total= $number1 * $number2; break;
             case "/" : $total= $number1 / $number2; break;
        } 

echo "Your result is ". $total;
?>

</body></html>