“I thought if you multiply two integers together, you get an integer. But apparently you don't in PHP. You get a floating point number, which gets bigger and bigger and that's okay. Until you get to factorial(171), and then you get "INF". I don't know what "INF" is. I think it's infinity actually. But in that case, it's probably wrong, because infinity is awfully big. Bigger than factorial(171).”