To find: number of ways of hanging 6 pictures on 4 picture nails.

There are 6 pictures to be placed in 4 places.

Formula:

Number of permutations of n distinct objects among r different places, where repetition is not allowed, is

P(n,r) = n!/(n-r)!

Therefore, a permutation of 6 different objects in 4 places is

P(6,4) = = = = 360

This can be done by 360 ways.