Riemann Sum app for iPhone and iPad

Riemann Sum is a calculator and graph application that is great for students learning Calculus.

Users can enter functions, input upper and lower bounds, and use the interactive slider to set the number of rectangles used to calculate the approximate area under a curve. You can delete existing cells by swiping left on the cell and selecting delete.

The graph is interactive, meaning you can scroll, zoom in, and zoom out.
At the bottom of the graph, you can find the approximate value of the area, rectangles used for calculations, and formula pertaining to the graph.