This is going to be the variance. And if you want the standard deviation, you can literally just get rid of this. You're taking the square root of both sides. So you take the square root of the variance, you get the standard deviation. That's why I got rid of that to the second power. And you want to take a square root of the right-hand side, just like that. Now, all I did right now is just to kind of conceptually set things up in our brain.