The Zhou Bi Suan Jing, or Chou Pei Suan Ching, is one of the oldest Chinese mathematical texts. 'Zhou' refers to the ancient Zhou dynasty (c. 1046 - 256 BCE) 'Bi' refers to the gnomon of a sundial.

The study is an anonymous collection of 246 problems encountered by the Duke of Zhou and his astronomer and mathematician, Shang Gao. Each question has stated their numerical answer and corresponding arithmetic algorithm. The Zhoubi suanjing contains one of the first recorded proofs of the Pythagorean Theorem.