In 264 CE, the Chinese mathematician Liu Hui used a method to determine the value of pi similar to that used by Archimedes.
Using a polygon with 192 sides, Liu Hui determined that 3.141024 < pi < 3.142704.
Using a much more faceted polygon, with 3,072 sides, he found that pi = 3.14159.
This extremely accurate calculation was actually improved upon by a father and son expert in mathematics and astronomy, Tsu Ch'ungChih and Tsu KenChih. Although the details of their calculations do not survive, the result they achieved was an approximation of pi = 355/113, approximately 3.1415929... This value is less than 10millionths of 1 percent from the value calculated today. Using the polygon method, they would have required a polygon of more than 24 thousand sides, with hundreds of square root calculations carried out to an accuracy of approximately 9 decimal places.
