In China's famous ancient mathematical monograph "Nine Chapters Arithmetic" (written in the first century AD), the law of addition and subtraction of positive and negative numbers was put forward for the first time: "Positive and negative numbers say: the same name has points, different names are beneficial, positive and negative, negative bears positive, its different names have points, the same name is beneficial, positive and negative."

Here, the name is a number, except subtraction, mutual benefit and division are the absolute values of two numbers, and nothing is zero.

In the present words: "The addition and subtraction of positive and negative numbers means that the subtraction of two numbers with the same sign equals the subtraction of their absolute values, and the subtraction of two numbers with different signs equals the addition of their absolute values. Zero minus a positive number is a negative number, and zero minus a positive number. The addition of two numbers with different signs is equal to the subtraction of their absolute values? The sum of two numbers with the same sign is equal to the sum of their absolute values. Zero plus positive number equals positive number, and zero plus negative number equals negative number. " This statement about the arithmetic of positive and negative numbers is completely correct and completely in line with the existing laws. The introduction of negative numbers is one of the outstanding contributions of mathematicians in China.