The GURPS Basic Set which contains rules for the paper and pencil roleplaying game designed by Steve Jackson describes an ability that you can bestow on a character you are creating.
Lightning Calculator – You have the ability to do math in your head, instantly. If you have this talent, then you (the player) may use a calculator at any time, to figure anything you want – even if your character is fleeing for his life at the time!
This description seems to imply that doing math and calculating are the same thing. Do you agree or disagree? Make your case.