刘徽的成就，除了圆周率算法，求解线性方程组（高斯消元法），等幂等积定理，更伟大的是（据English Wiki）

Through his work in the Nine Chapters, he could have been the first mathematician to discover and compute with negative numbers; definitely before Ancient Indian mathematician Brahmagupta （排23）started using negative numbers.

刘徽生活的魏晋时期，社会动乱但思想活跃。以后中国数学就走下坡路了。