So it's equal to pi x squared squared is x to the fourth. Pi x to the fourth dx. Now this expression right over here, this gave us the volume just of one of those disks, but what we want is the volume of this entire hat or this entire kind of bugle or cone-looking, or I guess you could say the front of a trumpet-looking thing. So how could we do that? Well, the exact same technique. What happens if we were to take the sum of all of these things? So let's do that.