And so I will say that that is the height of our first rectangle. Then we go over here, the left boundary of the second rectangle. We're now looking at the function evaluated at 1.5, so that is f of 1.5. That's the height. And so we get our second rectangle. Then we get, I could keep going like this, we get for this third rectangle, we have the function evaluated at 2. So we have the function evaluated at 2.