what are the number of onto functions from set A containing m elements to the set B containing n elements

The number of one-one functions from a set containing 2 elements to a set containing 3 elements is:

Find the the number of functions from a set A containing 5 elements into a set B containing 4 elements.

The number of functions from a set containing 3 elements into a set containing 6 elements is

Find the number of surjections from a set A containing 6 elements into a set B containing 2 elements.

The number of injections from Set - A containing 5 elements to a Set -B containing 6 elements is

The number of relations form a set containing melements to a set containing n elements is

Find the number of surjections (onto f) and from a set A containing 6 elements to a set B containing 2 elements.