奇数:1,3,5,7,9,11,13,15,17,19偶数:2,4,6,8,1,12,14,16,18,20质数:2,3,5,7,11,13,17,19合数:4,6,8,9,10,12,14,15,16,18,20奇数有10个,偶数有10个,质数有8个,合数有11个
奇数就是单10个,偶数就是双10个质数7个:2,3,7,11,13,17,19合数12个:4,5,6,8,9,10,12,14,15,16,18,20
10,10,9,11
奇数10