Zu Chongzhi (429-500), Chinese scientist, working with a compass. Zu was born in Nanjing, China. The Zu family were astronomers and handed down their mathematical and astronomical skills from father to son. In 462, Zu proposed a new calendar based on his calculations of the length of a year. The result was only 50 seconds away from the true value. He also improved the accuracy of pi to 355/113, a value not improved upon until 1000 years later.