: an instrument for performing calculations by sliding counters along rods or in grooves
: a slab that forms the uppermost member or division of the capital of a column
Illustration of abacus
Did you know?
Probably of Babylonian origin, an abacus is a calculating instrument that uses beads that slide along a series of wires or rods set in a frame to represent the decimal places. It is the ancestor of the modern digital calculator. Used by merchants in the Middle Ages throughout Europe and the Arabic world, it was gradually replaced by arithmetic based on Hindu-Arabic numerals. Though rarely used in Europe past the 18th century, it is still used in the Middle East, China, and Japan.