Mathematics is fun. It's like a video game, a good one. The kind that strikes just the right balance of difficulty, depth, and interaction. You're given a challenge to overcome, and a set of tools to do it. You can go out, guns blazing and counting every digit by hand, or you could set up some traps and go round and around it until you somehow stumble upon the right answer. It's just so, so frustrating sometimes.
I mean sometimes you can look up the answer at the back of the book or something, but jumping straight to the answer of a mathematics puzzle is way lamer than looking up the walkthrough for a video game. You can always blame the game designer if a game is frustrating, but when a mathematics problem is frustrating it's probably because you're stupid. And people don't like to feel stupid.
