Zhoubi suanjing (The Arithmetical Classic of the Gnomon and the Circular Paths of Heaven) (c. 100 B.C.E.-c. 100 C.E.)
Describes one of the theories of the heavens. Early Han dynasty (206 B.C.E -220 C.E.) or earlier. Book burning of 213 B.C.E..
States and uses the Pythagorean theorem for surveying, astronomy, etc. Proof of the Pythagorean theorem.
Calculations including with common fractions.