5040÷2=25202520÷2=12601260÷2=630630÷2=315315=7×9×5即5040=2×2×2×2×3×3×5×72倍数,2,4,8,16,3的倍数,3,9,5的倍数,5,7的倍数,72个数相乘有4×2+4×1+4×1+2×1+2×1+1×1=21个数3个数相乘有4×2×1+4×...