Zu Chongzhi (429-500) had a grandfather named Zuchang, who was an official in charge of royal architecture in Song Dynasty. Zu Chongzhi grew up in such a family and learned a lot from childhood. People praised him as an erudite young man. He especially likes to study mathematics and astronomical calendars, and often observes the movements of the sun and planets and makes detailed records. Emperor Xiaowu of Song heard about his fame. He was sent to work in Hualin Research Province, a government department specializing in academic research. He is not interested in being an official, but he can concentrate more on studying mathematics and astronomy there. In China, there were officials who studied astronomy in the past dynasties, and made calendars according to the results of astronomical research. By the Song Dynasty, the calendar had made great progress, but Zu Chongzhi thought it was not accurate enough. He created a new calendar based on the results of long-term observation. It is called "Daming Calendar" ("Daming" is the title of Emperor Xiaowu of Song Dynasty). The number of days in each tropical year measured by this calendar (that is, the time between winter and Sunday in two years) is only 50 seconds different from that measured by modern science. The difference between the number of days of measuring the moon circle and that measured by modern science is less than one second, which shows its accuracy. In 462 AD, Zu Chongzhi requested Emperor Xiaowu of Song Dynasty to issue a new calendar, and Emperor Xiaowu called his ministers to discuss it. At that time, Dai Faxing, the favorite minister of the emperor, came out against it, thinking that it was an odd behavior for Zu Chongzhi to change the ancient calendar without authorization. Zu Chongzhi refuted Defarge on the spot with his own research data. Dai Faxing relied on the emperor's love for him. He said arrogantly, "The calendar was formulated by the ancients, and future generations should not change it." Zu Chongzhi is not afraid at all. He said seriously, "If you have something to prove, just debate it. Don't scare people with empty talk. " Emperor Xiaowu of the Song Dynasty wanted to help Dai Faxing, and found several people who knew the calendar to argue with Zu Chongzhi, who was refuted by Zu Chongzhi one by one. But Emperor Xiaowu of Song Dynasty refused to issue a new calendar until ten years after Zu Chongzhi's death. The Daming calendar he created was only implemented. Although the society was very turbulent at that time, Zu Chongzhi still studied science tirelessly. His greater achievement is in mathematics. He once annotated the ancient mathematics book Nine Chapters Arithmetic and wrote a book Composition. His most outstanding contribution is to obtain quite accurate pi. After a long and arduous study, he calculated pi between 3. 14 15926 and 3. 14 15927, becoming the first scientist in the world to calculate pi to more than seven digits. Zu Chongzhi is a generalist in scientific inventions. He built a compass car, and the bronze man on the car always pointed south. He also built a "Thousand-Li Ship" and tried it on the Xinting River in the southwest of Nanjing, with a daily voyage of 100. He also uses hydraulic rotary stone mill to grind millet, which is called "water mill". In Zu Chongzhi's later years, Xiao Daocheng, who mastered the Song Guards, destroyed the Song Dynasty.