Abacus, << AB uh kuhs, >> is an ancient device used in China and other countries to perform arithmetic problems. It can be used to add, subtract, multiply, and divide, and to calculate square roots and cube roots. The abacus consists of a frame containing columns of beads. The beads, which represent numbers, are strung on wires or narrow wooden rods attached to the frame.
The abacus was used by the ancient Greeks and Romans. The Chinese abacus is called suanpan, which means counting, or reckoning, board. A typical Chinese abacus has columns of beads. The first column on the right is the ones column. The second column is the tens column. The third column is the hundreds column, and so on. In addition, the columns are divided by a crossbar. Each column has two beads above the crossbar and five below it. Each upper bead represents five units—that is, five ones, five tens, and so on. Each lower bead represents one unit. The number 153, for example, is represented by moving 3 lower beads in the ones column up to the crossbar, 1 upper bead in the tens column down to the crossbar, and 1 lower bead in the hundreds column up to the crossbar.
The Japanese abacus, called the soroban, used rods with just one bead above the partition and four beads below it. The electronic calculator made both types of abacus obsolete.
