The abacus is one of the earliest devices to be used in calculation, and still in use, in various forms, around the world today. The Chinese abacus is dived into two parts: the upper part has two beads (for our two hands) and the lower part has five beads (for the five fingers on each hand). Before wooden abaci were built, people used flat tables with lines drawn on them (the table abacus was popular in the Middle Ages) and we believe that the earliest forms were simply drawn in the dust or sand. Indeed the Semitic work abaq (for dust) is believed to be the origin of the name. The Romans used small limestone pebbles for calculation and moved them across lines in the dust. The Latin word for pebbles was calculi, from which we derive the modern terms calculus and calculate. Later, in England, the table abacus became known as a counting board or simply a counter. Merchants would have a counter in their shop on which the account would be calculated.
Abacus

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