Factorials are used eg. in probability (combinatorics) and set theory. A factorial is the number of different ways you can combine a specific number of elements. Eg three elements can be combined in six different ways.
Example: 3! = 3 * 2 * 1
Integer (n) | Fact (n!) |
---|---|
1 | 1 |
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 |
More:
21! = 21 * 20!
22! = 22 * 21!
23! = 23 * 22!
...