Javascript/FOR loop

Hi
Does anyone here know how to use the FOR loop in javascript
if yes then can they show me how to write a 20 times table.

 

Code:

<script type="text/javascript">
var i = 0
var num = 20
for (i=1; i <= 10; i++)
{
document.write(i + " times 20 is " + num)
document.write("<br />")
num = num + 20
}
</script>

That'll print them, change the code to suit.