The word Abacus is derived from the Greek "Abax" meaning counting board and the original types of Abacus were stone slates with dust covering them and a stylus used for marking numbers. Later this evolved into a slate with groves where rocks or other counters would be placed to mark numbers. Later it finally evolved into a framed device with beads sliding along bamboo rods. The abacus is thought to have appeared during circa 1200 A.D. in China; in Chinese, it is called the suan-pan. The classic Chinese abacus has two types of beads on the abacus, those in the lower deck, below the separator beam, and those in the upper deck above it. …
