# Factorial

In mathematics, the factorial of a non-negative integer `n`, 
denoted by `n!`, is the product of all positive integers less 
than or equal to `n`. For example:

```
5! = 5 * 4 * 3 * 2 * 1 = 120
```

| n     | n!                          | 
| ----- | --------------------------: |
| 0     | 1                           |
| 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           |

## References

[Wikipedia](https://en.wikipedia.org/wiki/Factorial)