And so when your actual is below your regression line, you're going to have a negative residual. So this is going to be negative one right over there. Now we can calculate the standard deviation of the residuals. We're going to take this first residual, which is 0.5, and we're going to square it. We're going to add it to the second residual right over here. I'll use this blue, this teal color. That's zero.