+23254 A factorial is a way to write a certain type of multiplication problem. Its symbol is an exclamation point '!'.
It starts with two definitions:
0! = 1
1! = 1
And then it continues with this style of multiplication
2! = 2 x 1 = 2
3! = 3 x 2 x 1 = 6
4! = 4 x 3 x 2 x 1 = 24
5! = 5 x 4 x 3 x 2 x 1 = 120
etc.
