Strange JavaScript Output when Multiplying

Question

I wrote a quick JavaScript for a simple calculation. When I ran the script it had a strange output that I can't explain...

The script was, in its most basic form this:

for (var a=0;a<100;a++) {
    var b= 3.6*a
    document.write( b + "<br />");
} 

Here's the demo: http://jsfiddle.net/uKa2G/

Expecting that I would get straight single or no decimal answers, but every few lines there would be a huge decimal.

If someone can explain why it would be appreciated.

Answer 1

If you're expecting no decimal then you have to parseInt().

for (var a=0;a<100;a++) {
    var b= 3.6*a;
    console.log( parseInt(b));
}