Maths: Why is 0! = 1?

09 Mar 2018 maths, factorial, intuition

Let’s find factorial of numbers from 0 to 4

0! = 1
1! = 1  (1)
2! = 2  (1 * 2)
3! = 6  (1 * 2 * 3)
4! = 24 (1 * 2 * 3 * 4)

Let’s go reverse

4! = 24 (1 * 2 * 3 * 4)
3! = 24/4 = 6
2! = 6/3  = 2
1! = 2/2  = 1
0! = 1/1  = 1 <- This is why