Zu Chongzhi likes mathematics since childhood, and has learned a lot of mathematics knowledge under the guidance of his father and grandfather. On one occasion, his father brought him a book "Weekly Parallel Calculations" from the bookshelf, which was a famous mathematical work in the Western Han Dynasty or earlier. The book says that the circumference of a circle is three times its diameter. So he measured the wheel with a rope and verified it, only to find that the circumference of the wheel is a little more than three times the diameter of the wheel. He went to measure the washbasin again and the result was the same. He thinks that the circumference is not exactly three times the diameter, so how much longer is the circumference than three times the diameter? Before the Han Dynasty, China generally used three as the value of pi, that is, "three circumference diameters are one". When calculating the circumference and area of a circle, there is a great error. On the basis of Liu Hui's scientific method of finding pi by secant method, Zu Chongzhi found pi is 3.1415927 > π& gt； 3. 14 15926。 This was the most accurate numerical value in the world at that time, and he became the first person in the world to make Pi accurate to the seventh place after the decimal point. It was not until 1000 years later that this record was broken by Europeans. The calculation of pi is Zu Chongzhi's outstanding contribution in mathematics. Some mathematicians abroad call π "ancestral rate".