And I want to take the sum of all of those disks. So I want to take, so the volume is going to be the sum over all of those disks. So x goes from zero, which is this bounding point, to x is equal to 1 1⁄2, times pi times one minus f of x squared. This is the area of the face of each of those disks. And then I multiply it times the depth of each of those disks. Now this is the volume of each of those disks, and I'm taking the sum of all of them. So this is the volume, this is the volume if I were to just rotate f of x around y is equal to one.