Wang Fan (228–266), courtesy name Yongyuan, was a Chinese astronomer, mathematician, politician, and writer of the state of Eastern Wu during the Three Kingdoms period of China.
[4] During the reign of the third Wu emperor Sun Xiu, Wang Fan served as a Central Regular Mounted Attendant (散騎中常侍) alongside He Shao, Xue Ying and Yu Si, and was given an additional appointment as a Chief Commandant of Escorting Cavalry (駙馬都尉).
During the reign of the fourth and last Wu emperor Sun Hao, Wang Fan became a Regular Attendant (常侍) alongside Wan Yu, Guo Chuo and Lou Xuan.
Sometimes Sun Hao liked to get drunk and have senior members teased by those in more junior ranks,[15] Wang Fan said Wan Yu was a low-born with an appearance like a tiger but a sheep's heart who received favour beyond his empty qualities.
The Sanguozhi says when Sun Hao held a banquet for the returning envoy to Jin Ding Zhong (丁忠), Wang Fan got very drunk and fell over.
[22] The third century local history Jiangbiao Zhuan (江表傳; "Account of the Lands Beyond the Yangzi") by Yu Pu[23] provides a very different tale.
[27] Lu Kai, the Imperial Chancellor of Wu during Sun Hao's reign, lamented Wang Fan's unfortunate end.
In addition, he gave the numerical value of π as 142 / 45 = 3.155...,[34][35] which, while an improvement on the Later Han and on Lu Ji's calculations,[36] was not as accurate as that given by the mathematician Liu Hui, who lived around the same time as him.