In how many ways 10 different books can be arranged in an almirah such that a particular book (1) is always taken (2) is never taken

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

In how many ways 10 different books can be placed in a almirah so that two specific books(i) always occur together(ii) never occur together.

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

Number of ways in which 15 different books can be arraged on a shelf so that two particular books shall not be together is

Number of ways in which 15 different books can be arraged on a shelf so that two particular books shall not be together is

In how many ways can 20 books be arranged on a shelf so that a particular pair of books shall not come together?

Find the number of ways in which 5 different books can be arranged on a shelf.