Well, two times one is two factorial, and where did we get that? Well, we wanted the first four, the first four factors of six factorial. So if you want, and that's where the four came from. We wanted the first four factors, and so the way we got two is we said six minus four. Six minus four, that's going to get us what we want to get, that's going to give us the number that we want to get rid of. So we wanted to get rid of two, or the factors we want to get rid of. So that's going to give us two factorial.