求50以内有6个约数有哪些?有过程

Question

如题所述

Answer 1

去掉所有的质数:
2,3,5,7,11,13,17,19,23,29,31,37,41,43,47
去掉几个平方数: 1,4,9,25,49
这样还有 30个数字
去掉11的倍数: 22,33,44
去掉13的倍数: 26,39
去掉17,19,23的倍数: 34,38,46
去掉三次方数: 8,27
还有20个数字: 6,10,12,14,15,16,18,20,21,24,28,30,32,35,36,40,42,45,48,50
其中,6,10,14,15,21,35只有四个约数
还剩下16个
12: 1,2,3,4,6,12
16: 1,2,4,8,16
18: 1,2,3,6,9,18
20: 1,2,4,5,10,20
24: 1,2,3,4,6,8,12,24
28: 1,2,4,7,14,28
30: 1,2,4,8,16,32
36: 1,2,3,4,6,9,12,18,36
40: 1,2,4,5,8,10,20,40
42: 1,2,3,6,7,14,21,42
45: 1,3,5,9,15,45
48: 1,2,3,4,6,8,12,16,24,48
50: 1,2,5,10,25,50
因此,合乎规定的有12,18,20,28,30,45,50等7个数字.

Answer 2

12:1,12,2,6,3,4 18:1,18,2,9,3,6 20:1,20,2,10,4,5 32:1,32,2,16,4,8 44:1,44,2,22,4,11 应该就只有这些了，如有错误，敬请帮忙改正！