Cheng Dawei, A Master of Abacus

Chinese abacus is a simple device for performing mathematical calculations. Known as the Fifth Invention of Ancient China, the abacus can perform addition, subtraction, division and multiplication; it can also be used to obtain square roots and cubic roots.

The Chinese abacus and zhusuan (reckoning by the abacus) were very important in ancient China, especially for businessmen. As a native of Land of Hui Merchants, famous mathematician Cheng Dawei has achieved quite a lot in abacus calculation skills.

Born in Xiuning County of Huizhou Prefecture nowadays called Huangshan City, Cheng Dawei (1533 ~ 1606), was a famous grand master of ancient abacus. He published the Suanfa tong zong (General source of computational methods) in 1592. That's why he has been known worldwide as "the great master of zhusuan". In Japan, he is worshipped as "the God of Arithmetics," and August 8 was established as the "abacus festival" in commemoration of him.

Cheng Da Wei lived in the latter half of the Ming dynasty which was a period of prosperity with increasing trade and commerce. It was also a period of relatively good stable government. A complex system of land tax led to a farmer's tax bill involving complicated reckoning of many different tax items. This resulted in both a need for mathematical skills by many people, and also led to efforts by local officials to simplify land-tax. Cheng Da Wei was probably directly involved in such efforts but, if not, he was certainly indirectly involved. The need for arithmetical skills led to the invention of the abacus and Cheng Da Wei's book General source of computational methods was an arithmetic book for the abacus. It is not an academic work on mathematics, rather it is a practical book aimed at assisting those who need to calculate.

In Cheng Dawei's former residence, which has been listed as a national key cultural relics protection unit, many quality abacuses are displayed, ranging from the smallest -- a finger ring abacus, to the biggest -- a door-shaped one, from the longest -- an abacus for extractions, to the strangest -- a round abacus, beadless abacus, and three-beaded abacus. Enduring interest in the ancient abacuses is evident by the ever-increasing number of visitors from all over the world.

The abacus is still in use today by shopkeepers in Asia and "Chinatowns" abroad. Asian schools still teach how an abacus is used, including a few schools in the West. Blind children are also taught to use the abacus.