So that's going to give us two factorial. So if we use six minus four factorial, then that's going to give us two factorial, which is two times one, and then these cancel out, and we are all set. And so this is one way, this is, you know, I put in the particular numbers here, but this is a review of the permutations formula, where people say, hey, if I'm saying n, if I'm taking n things, and I want to figure out how many permutations are there of putting them into, let's say, k spots, it's going to be equal to n factorial over n minus k factorial. That's exactly what we did over here, where six is n, and k, or four, is k. Four is k. Actually, let me color code the whole thing so that we see the parallel. Now, all of that is review, but then we went into the world of combinations, and in the world of combinations, we said, okay, permutations make a difference between who's sitting in what chair. So for example, in the permutations world, and this is all review, we've covered this in the first combinations video, in the permutations world, A, B, C, D, and D, A, B, C, these would be two different permutations. It's being counted in whatever number this is.