Excel 2007 : Simple math problem

I was trying to figure out a simple percentage using Excel 2007, and I'm a little confused.

A1=35
A2=45
A3=A1/(A1+A2)

The value of A3 displays as 0.

Well, I just about solved my problem because I've done similar formulae to get the answer of .4375. And now even the exact formula in different cells to get that answer.

Maybe it seems silly to still post, but can someone tell me why A3 continues to give me "0" after entering the formula different ways multiple times? Is this cell possessed by Satan?

Check the formatting of A3...it could be formatted to show zero at all times.....