Pi refers to the ratio of the circumference to the diameter of a circle on a plane. Zu Chongzhi worked hard to calculate the value of pi (л) to seven decimal places for the first time in the history of mathematics in the world, that is, between 3. 14 15926 and 3. 14 15927. He proposed an agreed rate of 22/7 and a secret rate of 355/ 1 13. This secret rate value was first put forward in the world, more than 1000 years earlier than that in Europe, so some people advocate calling it "ancestral rate". He compiled his mathematics research results into a book called Seal Characters, which was once regarded as a mathematics textbook by Chinese studies in the Tang Dynasty. His Da Ming Li introduced precession into the calendar for the first time. It is planned to set 39 1 year 144 Yan Yue. The length of a tropical year is 365.338+04438+0 days, and the error is only about 50 seconds. He is not only an outstanding mathematician and astronomer, but also an outstanding mechanic expert. Rebuild all kinds of exquisite machinery, such as South Guide Car and Thousand-mile Ship, which have long been lost. Besides, he also studies music. His works, such as Explaining the Analects of Confucius, Explaining the Classic of Filial Piety, Yi, Lao, Zhuang and the novel Yi Shu Ji, have long been lost.