Factorial Quiz

Again, the factorial of a positive integer n, written n!, is the product of all positive integers less than and equal to n.

5! = 5 * 4 * 3 * 2 * 1

Let's visualize how big these things get:

n	n!
2	2
3	6
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