So you add the squared distance for each of these points from i equals 1 to i is equal to n, and you divide it by n. So let's see what happens if we can, I don't know, maybe we want to multiply out the squared term and see where it takes us. So let's see. And I think it'll take us someplace interesting. So this is the same thing as the sum from i is equal to 1 to n. Let's see, this we just multiply it out. This is the same thing as x sub i squared minus, this is your little algebra going on here. So when you square it, I mean, we could multiply it out. We could write it x sub i minus mu times x sub i minus mu, so we have x sub i times x sub i, that's x sub i squared.