The Mod Function
What has modular arithmetic got to do with the real world?
The answer any experienced programmer should give you is "a lot". Not only is it the basis for many an algorithm, it is part of the hardware.
AI and Games Pioneer, A L Samuel
One landmark that stands out in programming history, is the first computer game. It wasn't space invaders and it wasn't anything to do with Mario. It was written by a man whose work dated from the dawn of the computing era, Arthur Lee Samuel.