bpystep, как вариант...
<!DOCTYPE html>
<html>
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1251">
<script>
function Calc() {
var a1,a2
a1=+document.getElementById('f1').value
a2=+document.getElementById('f2').value
alert(a1*a2)
return false
}
</script>
</head>
<body>
<form action='index.html' method='post' name='Select' onsubmit='return Calc()'>
<table width="100px">
<tr>
<td>
<b>1:</b>
</td>
<td width="50" >
<input id='f1' type="text">
</td>
</tr>
<tr>
<td>
<b>2:</b>
</td>
<td width="50" >
<input id='f2' type="text">
</td>
</tr>
<tr>
<td></td>
<td>
<input type='submit' name = 'Rezult' value='Результат'>
</td>
</tr>
</table>
</body>
</html>