<?php

/* Calculator */


if($submit)
{
   if($operator == '*')
   {
       echo $numa * $numb;
   } elseif($operator == '/')
   {
       echo $numa / $numb;
   } elseif($operator == '+')
   {
       echo $numa + $numb;
   } elseif($operator == '-')
   {
       echo $numa - $numb;
   }
} else { ?>
<form method="POST" action="<?php $_SERVER['PHP_SELF']; ?>">
 <input type="text" name="numa" size="10">
 <input type="text" name="operator" size="2">
 <input type="text" name="numb" size="10">
 <input type="submit" value="Calculate" name="submit">
</form>
<?php } ?>