Abacus (The counting Machine)

The abacus is an ancient calculating machine. Thissimple apparatus is about 5,000 years old and is thought tohave originated in Babylon. As the concepts of zeroandArabic number notation became widespread,basic mathfunctions became simpler,and the use of the abacus dimin-ished. Most of the world employs adding machines,calcu-lators,and computers for mathematical calculations,buttoday Japan,China,the Middle East,and Russia still usethe abacus,and school children in these countries are oftentaught to use the abacus. In China,the abacus is called asuan pan,meaning counting tray. In Japan the abacus iscalled a soroban. The Japanese have yearly examinationsand competitions in computations on the soroban.Before the invention of counting machines,peopleused their fingers and toes,made marks in mud or sand,put notches in bones and wood,or used stones to count,calculate,and keep track of quantities. The first abaciwere shallow trays filled with a layer of fine sand ordust. Number symbols were marked and erased easilywith a finger. Some scientists think that the term abacuscomes from the Semitic word for dust,abq.

A modern abacus is made of wood or plastic. It isrectangular,often about the size of a shoe-box lid. With-in the rectangle,there are at least nine vertical rodsstrung with movable beads. The abacus is based on thedecimal system. Each rod represents columns of writtennumbers. For example,starting from the right and mov-ing left,the first rod represents ones,the second rod rep-resents tens,the third rod represents hundreds,and soforth. A horizontal crossbar is perpendicularto therods,separating the abacus into two unequal parts. The moveable beads are located either above or below thecrossbar Beads above the crossbar are called heaven pushed up to the crossbar. Number two would require two earth beads. For number five, only one heaven bead would to be pushed to the crossbar. The number six would require one heaven (five units) plus one earth (one unit) bead. The number 24 would use four earth beads on the first rod and two earth beads on the second rod. The number 26 then, would use one heaven and one earth bead on the first rod, and two earth beads on the second rod. Addition, subtraction, multiplication, and division can be performed on an abacus. Advanced abacus users can do lengthy multiplication and division problems, and even find the square root or cube root of any number.

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