Javascript

Here is some javascript which creates this:

<html>
<body>
<script>
function show_equation()
{
var action=prompt("What would you like to do? Add, Subtract, Multiply or Divide?","Add");
var n1=document.vari.no1.value;
var n2=document.vari.no2.value;
switch(action)
{
case (action == "add" || "Add"):
 alert(Number(n1)+Number(n2))
 break;


case (action == "subtract" || "Subtract"): 
 alert(Number(n1)-Number(n2))
 break;
 case (action == "multiply" || "Multiply"):
 alert(Number(n1)*Number(n2))
break;
 case (action == "divide" || "Divide"):
 alert(Number(n1)/Number(n2))
break;
}
}
</script>
<form name="vari">
<input name="no1" type="text">
<input name="no2" type="text">
<input name="calculate" type="button" onclick="show_equation()" value="Calculate" />
</form>
</body>
</html>
</body>
</html>