The abacus (plural abaci or abacuses), also called a counting frame, is a very early computational device used for simple calculations. Abacuses come in different designs, some use beans or stones moved in grooves of sand or on tablets of wood, stone, or metal. A framed abacus consists of a frame with beads sliding on wires. There are between seven and 15 sets of beads and can be constructed in different numerical bases.
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