Question

why the zero factorial equals to one

Answer 1

It's Pretty simple buddy, Here is the reason for it,

We know that n! = n*(n-1)*(n-2)*...........*3*2*1,

And it is important to remember this ,
n! = n(n-1)!,
Now using the above formula we can tell why zero factorial is 1,

Divide the above equation with n on both sides,
=> n!/n = n(n-1)!/n
=>n! / n = (n-1)!,

Now keep 1 in place of n, i.e  n = 1,
=> 1! / 1 = (1-1)!,
=> 1/1 = 0!,
=> 0! = 1,

So 0! is equal to 1, I hope this reason is understandable ,

Hope you understand,Have a great day !,
Thanking you, Bunti 360 !