And a Riemann sum is just breaking up this area into rectangles and then finding the total area of those rectangles. And then there's a couple of ways you could do it. You could use, for each rectangle, you could use the left boundary as the height, or you could use the right boundary as the height. And so they tell us to use a right Riemann sum. A right Riemann sum. So for each of the rectangles, for each of the intervals, we're going to use the value of our function on the right side to approximate the area. So let's do that.