Choosing the greater-coordinate boundary of each subinterval determines where the function is sampled. That sampled value becomes the height of the corresponding rectangle, while the subinterval width determines its horizontal extent. Summing these rectangle contributions produces an approximation to the accumulated area, linking endpoint selection to the geometry behind Riemann sums.
Refining the partition reduces the width of the pieces used to construct the rectangles. Because the right-endpoint values are then taken over smaller subintervals, the resulting sum can move toward the exact definite integral. This limiting behavior is central to connecting a finite numerical estimate with the integral it is intended to approximate.
A partition breaks the original interval into multiple subintervals, and each subinterval has its own right boundary. The method evaluates the function at every one of those boundaries rather than using a single endpoint for the whole interval. This repeated sampling creates a sequence of rectangle heights that collectively represents the interval's accumulated area.
Start with the interval and divide it into subintervals. For each piece, identify its greater-coordinate boundary, evaluate the function there, and use that value as the rectangle height. Pair each height with the corresponding subinterval width, then add the rectangle contributions. Repeating the calculation with a finer partition gives a more refined estimate.
Right-endpoint sums are useful when a definite integral must be estimated numerically rather than treated only as a limiting object. They convert function values into rectangle areas and provide a finite approximation that can be compared with the exact integral. The same comparison supports error analysis by showing how approximation changes as the partition is refined.
In mathematics, the construction illustrates how Riemann integration builds an integral from sums over subintervals. Each sampled function value contributes a rectangle, and the limiting process explains why those finite sums can represent accumulated area. Thus, the technique gives a concrete geometric route from partitioning an interval to the analytic idea of a definite integral.