1~20的自然数中奇数有:1,3,5,7,9,11,13,15,17,19
偶数为2,4,6,8,10,12,14,16,18,20
质数有2,3,5,7,11,13,17,19
合数有4,6,8,9,10,12,14,15,16,18,20
08-06 60阅读
06-30 198阅读
08-09 65阅读
10-11 255阅读
07-23 125阅读
07-02 125阅读
08-04 357阅读
04-20 115阅读
03-29 185阅读
09-25 208阅读