The abacus was a great invention in ancient China and has
been called by some Western writers "the earliest calculating machine in the world."
The abacus has a long history behind it. It was already
mentioned in a book of the Eastern Han Dynasty, namely Supplementary Notes on the Art of Figures written by Xu Yue about the year 190 A. D. Its popularization occurred at the latest during the Song Dynasty (960-1127), when Zhang Zeduan painted his Riverside Scenes at Qingming Festival. In this famous long scroll, an abacus is clearly seen lying beside an account book and doctor's prescriptions on the counter of an apothecary's. During the Ming Dynasty (1368-1644), the abacus was introduced into Japan.
Abacuses are easy to make, handy to carry around and
quick to give the answers, provided one knows how to move the
beads. They have been in use, therefore, down to this day.
They are made in different sizes, and the largest known abacus, measuring 26 centimetres high by 306 centimetres long with 117 rods (for as many digits), is over a hundred years old and is kept at Darentang, a well-known traditional pharmacy in Tianjin.
The beads on an abacus may be round or rhombus in shape.
Traditionally, there are two beads above the horizontal bar and five below. Simplified modern versions have one bead above and four or five below. The methods of calculation remain unchanged.
At a time when the world has entered the age of electronics, the abacus still enjoys undiminished vitality in China. Tests have shown that, for operations of addition and subtraction, the abacus is still faster than the electronic calculator. China developed in 1980 an "electronic abacus " which combines the speed of traditional addition and subtraction methods with those of the modern calculator at multiplication and division. It is a happy example of the integration between the East and West, the native and the modern.