Abacus

Pronunciation: /ˈæb ə kəs/ ?

Plural: abacuses or abaci.

A rectangular wood frame. 13 wooden dowels are set in the frame at regular intervals. Each wooden down is divided into two sections by a wooden crossbar. Above the crossbar are two beads. Below the cross bar are five beads.
Figure 1: Abacus.

An abacus is a device with sliders and beads used for counting and arithmetic. Abacuses have been used throughout the world since before 2300 BCE. Ancient abacuses were counting boards with markers arranged in patterns that represented a number. In more modern times, an abacus consists of a frame, multiple sliders and beads. The beads are slid long the sliders to represent numbers. In most abacuses used today, the two beads on the top each represent 5 and the five beads on the bottom each represent 1.

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Abacus. 2010-10-13. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/a/abacus.html.

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2010-10-13: Initial version (McAdams, David.)

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