Parents often scoff at the powerful calculators their children use for math classes, noting that they had to learn with slide rules. A device that predates both tools, however, is the focus of this unique site. The abacus has roots in the fifth century B.C., and still sees limited use in various parts of the world. A very thorough overview is provided online, with interactive applets that teach the user how to perform addition, subtraction, multiplication, and division with an abacus. Several excerpts from a textbook demonstrate square and cube root extraction. Historical perspectives are given that trace the use of the abacus through time and different civilizations.