Zhu Chongzi was born in Nanking in 429 A.D. Zhu’s family had good knowledge in astronomy and calendar study. He was posed to math and astronomy knowledge when he was very young.

Zhu Chongzi enjoyed good reputation and glory around his hometown when he became adult. He was appointed to do the research job by Xiao Wu Di (Song’s emperor).

From 494 to 498, he has been government chief official in Changshui and enjoyed the forth level of bonus in government. In the situation of wars and rebellions, he wrote a article called An Bian Lun , which in English means about controlling and stabling of Frontier of the country. He advised the government to assart the field and develops the agriculture and stables the people and strengthens country safety. Zhu Chongzi died in 500 A.D. in his 72. Zhu Chongzi’s son was also a great mathematician in ancient China. In order to remember the great scientist, the mountain on the back of the moon was named after Zhu Chongzi.

Furthermore, he get a huge contribute in Archimedes, and these achivements include Daming calendar, distinguishing the Sidereal Year , the Tropical Year and deriving two approximations of pi, which held as the most accurate approximation for π for over nine hundred years, and calculating one year as 365.24281481 days, which is very close to 365.24219878 days as we know today.

1. The historical significance of that contribution

As a boy Zu Chong-Zhi loved science and assiduously studied works on astronomy and mathematics. He did not believe everything ancients said with a blind faith and dared to correct their mistakes. His diligence resulted in many inventions. He made reforms to the south£pointing carriage. Whichever way it moved the wooden human figure on it pointed always to the south. His inventions like doubleshafted singlewheeled cart, hydraulic mill, and thousandli boat played a great role in the production life of that time. His most outstanding achievement is the calculation of the ratio of the circumference of a circle to its diameter pi, "Zhou Bi", a mathematical classic of Eastern Jin Dynasty 317420, believes that the ratio of the circumference to the diameter was 3 to 1. Between the year 1 to 5 when Liu Xin made a standard measure called "jialianghu" he improved the ratio to 3.145. Liu Hui, a mathematician of the Three Kingdoms period, claimed that "3 to 1" was rather a ratio of the circumference of the inscribed hexagon with the diameter of the circle than a ratio of the circumference of the circle with the diameter. He discovered that the more sides a polygon had the closer its circumference was to that of a circle. Thus he initiated the method of cyclotumy and obtained the approximate value of pi to be 3.14. It was believed that Zu Chong-Zhi adopted his cyclotumy. He carved up the circumference again and again and made long and meticulous calculations and obtained the result that the value of pi was between 3.1415926 to 3.1415927. The fractional value 355/113 Zu Chong-Zhi calculated for pi is quite unique in the history of mathematics. Ancient Greek didn't accomplish it. The Indians had no knowledge in this field. The very mathematical Arabians weren't able to obtain this result. In Europe it was obtained 1,000 years later. Regretfully, Zu Chong-Zhi's method of calculation was lost. We only find some records about Zu Chong-Zhi in "History of the Sui Dynasty". It was according to the methods he used in calculating the pi