Two n digit integers are said to be equivalent if one is a permutation
of the other. for eg. 10075 and 01057 are equivalent.
Find the number of 5 digit integers such that no two are equivalent
This means permutations are not to be considered.
9x10x10x10x10 (assuming repetition allowed) -5!-5!/2!-5!/3!-5!/4!-5!/2!.3!-5!/2!.2! etcetra which is subtracting all permutations.