Zu Chongzhi's outstanding achievement in mathematics is about the calculation of pi. Before Qin and Han Dynasties, people used the diameters of one week and three weeks as pi, which was the ratio in ancient times. Later, it was found that the error of pi was too large, and pi should exceed the diameter of one week and three weeks, but there were different opinions on how much was left. Until the Three Kingdoms period, Liu Hui put forward a scientific method to calculate pi-pi secant method, which connects regular polygons inside a circle to approximate the circumference of a circle. π=3. 14 is obtained, and it is pointed out that the more sides inscribed in a regular polygon, the more accurate the π value is. On the basis of predecessors' achievements, Zu Chongzhi worked hard and repeatedly calculated that π was between 3. 14 15926 and 3. 14 15927.
What method did Zu Chongzhi use to get this result? It is impossible to check it now. If we imagine that he will find it according to Liu Hui's secant method, we must work out the polygons inscribed in the circle 16384. How much time and labor it takes! It can be seen that his tenacious perseverance and intelligence in academic research are admirable. It has been over 1000 years since Zu Chongzhi calculated the secret rate and foreign mathematicians got the same result. In order to commemorate Zu Chongzhi's outstanding contribution, some foreign mathematical historians suggested that π = be called the ancestral rate.
Zu Chongzhi exhibited famous works at that time and insisted on seeking truth from facts. He compared and analyzed a large number of materials calculated by himself, found serious mistakes in the past calendars, and dared to improve them. At the age of 33, he successfully compiled the Daming Calendar, which opened a new era in calendar history.
Zu Chongzhi and his son Zuxuan (also a famous mathematician in China) solved the calculation of the volume of a sphere with ingenious methods. At that time, they adopted a principle: evenly matched, but the products were no different. That is to say, two solids located between two parallel planes are cut by any plane parallel to these two planes. If the areas of the two sections are always equal, the volumes of the two solids are equal. This principle is called in western languages.