The abacus, invented by the Chinese a few thousand years ago, is an instrument for calculating. It has two sections: the top section has rods of two beads, while the bottom section has roads of five beads. The number of rods is always odd in number.

The Japanese abacus, modified from the Chinese, has rods of one bead in the top section and four beads in the bottom section.

Before the invention of the calculator, Chinese business people often used the abacus at the end of a day’s business for calculation. When a shop opened for a day’s business, it was common practice for the boss to shake the abacus hard, causing the beads to make a loud noise against the frame. This was supposed to ensure that the day’s collection would be so good that the boss would be kept busy moving the beads along the rods at the end of the day.

The abacus is considered the “mother” of calculating instruments and continues to be used today, even though its role has been much overshadowed by the introduction of the electronic calculator.