can u plz explain how 0!=1 and not 0??

n! denotes the numberof ways n objects can be arranged in row.

therfor 0! means number of ways of arranging 0 object that is oone way ?.

therfor 0!=1

 

or,

 n!=n(n-1)!

putting n=1 in this

1!=1*(0!)

therfor 0!=1