also called Seki Kōwa
born с 1640, Fujioka, Japan
died Oct. 24, 1708, Edo
the most important figure of the wasan ("Japanese calculation") tradition that flourished from the early 17th century until the opening of Japan to the West in the mid-19th century.
He was adopted at an early age by Seki Gorōzaemon, a samurai official with the Bureau of Supply in Edo, to carry on the Seki family name. He assumed various positions as an examiner of accounts for the lord of Kōfu, Tokugawa Tsunashige (until 1678), and then his son, the future shogun Tokugawa Ienobu (see Tokugawa period ). Seki's most productive research was in algebra, a field in which he created powerful new tools and provided many definitive solutions. He was instrumental in recovering mathematical knowledge from ancient Chinese sources. He substituted a tabular notational system for the cumbersome Chinese method of counting rods, thereby simplifying the handling of equations with more than one unknown.