And now you can see for any one of these subdivisions, our rectangles are underestimates of the area under the curve. Under, underestimate. And that's because, once again, in this particular case, the function never increases. It's either decreasing or staying flat. So if you use the value of the function at the right edge, it's going to be smaller, it's never going to be larger than the value that the function takes on in the rest of that subdivision. And so we are continuously underestimating. We're missing all of this area right over there is not being included, so we have an underestimate.