Zu Chongzhi was a Chinese mathematician, astronomer and mechanic. He was born in a well-educated family. As excellent engineer, Zu's grandfather taught him science. From an early age, Zu (show) great intelligence and curiosity, with special interests mathematics and astronomy. Today we know Zu Because he was the (one) person to find out that pi falls between 3.1415926 and 3.1415927, and his result remained tht most accurate value in the world for more than 900 years. Zu also worked out the close value of pi to be 355/113, which he called "close ratio". This ratio was so hard to get a Japanese mathematician named it "Zu's ratio".
It is not clear how Zu became interested in (find) the value of pi, yet people have told stories about him. For a long time in the past, people believed that a circle's circumference was three times its diameter. Zu was not sure about this result and wanted to prove it (he). He used a rope (measure) the circumference of a wheel. Then he folded the rope into three equal parts and compared it with the diameter of the wheel. No matter how many wheel he measured, the diameter of the wheel was always (short) than a third of the circumference. As a result, Zu decided to work out a more accurate ratio. After years of hard work, he (final) worked out the value of pi.
