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.