Mathematical probability of chess games

okay, last night I figured out that there are 400 possible openings for a game of chess ( with a counter move for all 20 of white’s possible opening moves )

Now, does anybody know how many possible full games are possible on a chess board. I wouldn’t even know where to begin to solve this, but I doubt its like Pi. It should be a finite number. Anybody want to help out?

blasted security settings on our connection out here immensily limits what sites I can and can not go into. So sadly I won’t be able to see the answer until I get back. But regardless thanks Ben.