The abacus is a computing device on which arithmetic calculations are performed by sliding counters (beads, pebbles, or flat discs) along rods, wires or lines. The instrument may have originated in ...

The Russian abacus (tchoty) is held so that counters move crosswise. It has no crossbar, and all counters in one row have the same value. Most rods have ten counters. An occasional row has fewer, to ...