This applet shows how upper and lower Riemann sums can approximate an integral [math]\int^b_a f(x) \, \textrm{d}x[/math][br]Further, they show that as the number of strips [math]n[/math] increases, the Riemann sums converge to true value of the definite integral.[br]Input your own function into the textbox and set the limits to different values.