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Zu Chongzhi

Zu Chongzhi (425-500), born in Fanyang (now Laiyuan County in Hebei Province), was a great mathematician and astronomer during the Northern and Southern Dynasty (220-581). His main contribution to the development of science and technology includes the computation of pi, the calculation of the volume of sphere, the compilation of the Daming Calendar (462), and the invention of the south-pointing carriage.

Zu Chongzhi's main contribution to math is the computation of pi. Records show that Zu worked out the numerical value of pi -- between 3.1415926 and 3.1415927. It was the most advanced achievement worldwide at that time. Such precision was not surpassed until the 15th century when Al'Kashi, a native of Samarkand (now Uzbekistan), calculated pi using a similar method. To honor Zu's great contribution to math, some foreign math historian suggested calling pi "Zu Lv (the rate of Zu)". It is astonishing that Zu made the calculation even before the invention of the abacus, so he did all the work using nothing more than wooden counting sticks.

Zu Chongzhi and his son, Zu Geng, also managed to put forward the formula for computation of the volume of a sphere. Zhui Shu by Zu Chongzhi, one of the ten books on Suan Jing, was adopted as the textbook for mathematics in the Tang Dynasty (618-907).

In astronomy, Zu Chongzi created the Daming Calendar, taking into consideration the precession of the equinoxes for the first time in China. This was a major breakthrough in the history of Chinese calendar.

Zu was successful in producing a new system, but the new idea got tangled up in red tape. Ministers of the imperial court spent two years arguing about whether they should use the new Daming Calendar and might have gone on even longer if the emperor of the time hadn't passed away. Zu never saw his Daming Calendar put to use. A decade after Zu's death, the Calendar was at last recognized with years' of efforts by Zu's son.

Zu was also good at machine making. He invented the south-pointing bronze carriage and 1000-li Boat which could travel 100 li (1 li = 1/2 kilometers) in a day.

Zu was one of the few Chinese mathematicians to have a lunar feature named after him. People named a lunar crater at the back of the moon Zu Chongzhi in commemoration of him. Crater Zu Chongzhi (listed in the International Astronomical Union's handbook as Crater Tsu Chung Chi) is 28 km wide and located about 20 degrees north of the moon's equator. And the planet 1888 was named "Planet Zu Chongzhi".

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