can u give me the method to find the factorial of zero ?
What is the definition of the factorial?
Alternatively, there's exactly one way to arrange an empty set.
I highly doubt the OP would be able to make heads or tails of this.
[tex]n! = n(n-1)![/tex]
Work with this definition, it's all you need.
So your answer to the original question is that [itex]0!= 0(-1)![/itex]? But what is (-1)!?
(Yes, you can write that 1!= 1(0!) and, if you know that 1!= 1, then it follows that 0!= 1. But better is just to state the basic definition of n! that asserts 0!= 1 for as part of the definition.)
Separate names with a comma.