素数与复合数的关系、正整数是素数的条件

The Relationship between Prime and Composite Number as well Positive Integer being a Condition of Prime Number

在"奇合数的分解公式、素数及筛法"[1]中给出的奇合数10个分解公式的基础上,进一步研究复合数之间、素数与复合数之间存在的数量关系,并且证明了个位数为1,3,7,9的正整数是素数的充要条件.

This essay expounded and proved the relationship between composite number each other,and the quantitative relationship between composite and prime number. It also gave and proofed that the unit position digit,when it is the positive integer of 1,3,7,9 respectivelly,is the necessary sutticient condition of prime number.