There are only about 35 legal choices for each chess move, but the choices multiply exponentially to yield something like 1050 possible board positions—too many for even a computer to search exhaustively. That’s why it took until 1997 for a computer, Deep Blue, to defeat the human world chess champion.
I've talked with people about the amount of chess moves and all combinations and it is an extremely large number. You could calculate it by hand, but then you run into the issue like how people were trying to calculate more and more digets of pi. It could take decades. This is why computers are so extremely useful. The combinations of chess moves was actually an unsolved equation, among others like number of soduku game combinations and so on.