The Law and Discipline of Sui Shu records as follows: "At the end of the Song Dynasty, South Xuzhou engaged in Zu Chongzhi's more secret method. If the diameter of a circle is 100 million, the circumferential abundance is three feet, one foot, four inches, one minute, five millimeters, nine seconds, seven seconds, and three feet, one foot, four inches, five millimeters, nine millimeters, two seconds, six seconds, and the positive number is between the remainder and two limits. Density: circle diameter 1 13, circumference 355. Regarding the rate, the diameter of the circle is seven, and it is on the 22nd of the week. "
The record points out that Zu Chongzhi made two major contributions to pi:
Firstly, pi is 3. 14 15926.