And so if I have three spaces, how many ways can I arrange an A, B, and C in those three spaces? Well, A can go into three spaces. It can go into any of the three. A can go into any of the three spaces. Then B would have two spaces left once A takes one of them. And then C would have one space left once A and B take two of them. So there's three times two times one way to arrange three different things.