While the abacus was used for a wider purpose such as accounting, sangi was used exclusively by wasan mathematicians for calculating with Tengen-jutsu (the theory of algebraic equations developed in China) and so on.
そろばんは会計等広く用いられたのに対し、算木は専ら和算家によって、天元術（中国の代数方程式の理論）などの計算に用いられた。