" In how many ways "7" pictures can be hanged on "9" pegs? "

In how many ways 7 pictures can be hung from 5 picture nails on a wall?

In how many ways 7 pictures can be hung from 5 picture nails on a wall?

In how many ways the internal energy can be changed ?

In how many ways 7 books can be arranged from 10 books?

In how many ways can 6 pictures be hung from 4 picture nails on a wall?

In how many ways 12 different books can be separated into 3 equal groups. In how many ways they can be distributed among 3 persons equally

In how many ways can 7 different books be arranged on a shelf? In many ways three particular books are always together?