Why is the factorial of 0 equal to 1?

Question

Wouldn’t this also mean that 1!=0!, why is this true?

In: 383

Answer 1

That’s really just a convention that greatly simplifies most formulas. It also makes sense in terms of combinatorics as there’s only 1 way to arrange nothing (n! is the number of possible permutations of n distinct items, that is without repetitions)