编辑本段20 以内的数的阶乘: 以下列出0 至20 的阶乘: 0!=1,注意(0 的阶乘是存在的) 4!=24,5!=120, 6!=720, 7!=5,040, 8!=40,320 9!=362,880 10!=3,628,800 11!=39,916,800 12!=479,001,600 13!=6,227,020,800 14!=87,178,291,200 15!=1,307,674,368,000 16!=20,922,789,888,000 17!=355,687,428,096,000 18!=6,402,373,705,728,000 19!=121,645,100,408,832,000 20!=2,432,902,008,176,640,000 另外,数学家定义,0!=1,所以0!=1!