Question

在1到100的全部自然数中既不是八的倍数也不是五的倍数有多少个？

Answer 1

1,2,3,4,6,7,9,11,12,13,14,17,18,19,21,22,23,26,27,28,29,31,33,34,36,37,38,39,41,42,43,44,46,47,49,51,52,53,54,57,58,59,61,62,63,66,67,68,69,71,73,74,76,77,78,79,81,82,83,84,86,87,89,91,92,93,94,,97,98,99共70个。1到100中，5的倍数有20个，8的倍数有12个，既是8的倍数，也是5的倍数有2个所以有70个。