And then this simplifies to, can't do much on this side, so the sum from i is equal to 1 to n of x sub i squared over n. And then see, we have minus 2 mu squared plus mu squared. Well, that's the same thing as minus mu squared. Minus the mean squared. So this, already, we've kind of come up with a neat way of writing the variance. You can essentially take the average of the squares of all of the numbers, in this case a population, and then subtract from that the mean squared of your population. So this could be, depending on how you're calculating things, maybe a slightly faster way of calculating the variance. So just playing with a little algebra we got from this thing, where you have to, each time, take each of your data points, subtract the mean from it, and then square it.