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 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 ...

How to use the abacus became a compulsory subject at elementary schools in Japan in 1935. Today, soroban lessons are included in math classes for third- and fourth-graders. In 1986, there were ...