1. Reply to comment so that the user is notified.
2. Click improve question and put your code in the actual question instead of in a comment.
3. You can't do it like that because 123.40 is the same exact value as 123.400 and 123.4000 so you'll have to put it into a string or format it with that many places. For example you can do:
var num = 123.40;
num = num.toFixed(2);