Enter a sequence of integers. If the numbers are part of a known sequence, you will find out quick-smart.
http://www.research.att.com/~njas/sequences/index.html

A powerpoint show on the sum of an infinite geometric series by Joe Mellor, based on a presentation by Ray Cannon.

The Golden Rectangle is a plot created by starting with a rectangle, chopping off successive squares, and drawing quarter circles with a radius equal to the side of the square that was cut.
http://nlvm.usu.edu/en/nav/frames_asid_133_g_3_t_1.html?open=instruction...