0 factorial is defined as 1 because it represents the number of ways to arrange 0 objects.

• 0! is the product of all positive integers less than or equal to 0, which is 1.

• It is a convention in mathemati...read more

n! =n*(n-1)!

Put n =1 here

1!=1*(1-1)!

1!=1*0!

1!=0!

Therefore 0!=1!