Zu Chongzhi, a mathematician in the Northern and Southern Dynasties, further obtained the π value accurate to 7 decimal places (AD 466) by using the method of circle cutting, and gave the insufficient approximation of 3. 14 15926 and the excess approximation of 3. 14 15927, and also got two approximate fractional values with the density of 355.

In order to commemorate Zu Chongzhi's contribution to the development of China's pi, this calculated value was named "Zu Chongzhi pi" after him, or "ancestral rate" for short.

Extended data:

1. Pi, generally expressed by π, is a common mathematical constant in mathematics and physics. It is defined as the ratio of the circumference to the diameter of a circle. It is also equal to the ratio of the area of a circle to the square of its radius. Accurate calculation of geometric shapes such as circle perimeter, circle area and sphere volume is the key. Analytically, π can be defined as the smallest x >；; 0 makes sin(x) = 0.

2. When Chinese mathematician Liu Hui annotated Nine Chapters Arithmetic (AD 263), he only used a regular polygon inscribed in a circle to find the approximate value of π, and also got the π value accurate to two decimal places. His method was later called the secant circle method, which contained the idea of seeking the limit.

3. Many mathematicians have studied pi in history, among which Archimedes, Ptolemy, Zhang Heng and Zu Chongzhi are famous. They try to calculate the value of pi in their own country by their own methods. The following are the research results of pi around the world.

References:

Zu Chongzhi-Baidu encyclopedia

Circumcision-Baidu Encyclopedia