祖冲之
Zu Chongzhi is known to have computed between 3.1415926 and 3.1415927, which was correct to seven decimal places. He gave two other approximations of: π ≈ and π ≈ . The latter fraction is the best possible rational approximation of using fewer than five decimal digits in the numerator and denominator. Zu Chongzhi's result surpasses the accuracy reached in Hellenistic mathematics, and would remain without improvement for close to a millennium.