What is the factorial of "0"?

8! = 40320
7! = 8!/ 8 =5040
6! = 7!/ 7=720
5! = 6!/ 6 =120
4! = 5!/ 5 = 24
3! = 4!/ 4 = 6
2! = 3!/ 3 =2
1! = 2!/ 2 =1
0! = ?
so 0! = 1!/ 1 = 1/1 =1

now what is (-1)! ?
(-1)! = 0! / 0 = 1 / 0 = infinity, just kidding there is no negative factorial

1

0! = 1

is 1

it is 1

1

1

1

1

0! = 1