Instead, mathematical progress became focused on computational tools. In 15 century, abacus came into its "suan pan" form. Easy to use and carry, both fast and accurate, it rapidly overtook rod calculus as the preferred form of computation. "Zhusuan", the arithmetic calculation through abacus, inspired multiple new works. "Suanfa Tongzong" (General Source of Computational Methods), a 17-volume work published in 1592 by Cheng Dawei, remained in use for over 300 years. Zhu Zaiyu, Prince of Zheng used 81 position abacus to calculate the square root and cubic root of 2 to 25 figure accuracy, a precision that enabled his development of the equal-temperament system.