In 462 AD, Zu Chongzhi requested Emperor Xiaowu of Song Dynasty to issue a new calendar, and Emperor Xiaowu called ministers to discuss it. At that time, Dai Faxing, one of the emperor's minions, stood out against it and thought that it was deviant for Zu Chongzhi to change the ancient calendar without authorization. Zu Chongzhi refuted Defarge on the spot with his own research data. Relying on the emperor's favor, Dai Faxing said arrogantly: "The calendar was formulated by the ancients and cannot be changed by future generations." Zu Chongzhi is not afraid at all. He said very seriously, "If you have a solid basis, argue it out. Don't scare people with empty talk. " Emperor Xiaowu of Song wanted to help Dai Faxing, and found some people who knew the calendar to argue with Zu Chongzhi, but Zu Chongzhi refuted them one by one. However, Emperor Xiaowu of Song still refused to issue a new calendar. It was not until ten years after Zu Chongzhi's death that his Da Ming Li was put into practice. Although the society was very turbulent at that time, Zu Chongzhi 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 get 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 kind of compass, and the copper man in the car always pointed south. He also built a "Thousand-Li Ship" and tried it in Xinting River (now southwest of Nanjing). It can sail 100 Li a day. He also used hydraulic power to rotate the stone mill, pounding rice and grinding millet, which was called "water hammer mill". In Zu Chongzhi's later years, Xiao Daocheng, who mastered the Song Guards, wiped out the Song Dynasty.