In how many of the permutations of `n` thing taken `r` at a time will three given things occur?

The number of circular permutations of 8 things taken 4 at a time is

The number of circular permutations of 8 things taken 4 at a time is

2.The number of permutations of 8 things taken at a time is 1680, Then r=

The number of permutations of n things taken r at a time if 3 particular things always occur is

Find the number of permutations of n things taken r at a time in which two particular things : (i) always occur (ii) never occur.

No.of circular permutations of 15 things taken 5 at a time in one direction is:

Find the number of permutations of n different things taken r at a time such that two specific things occur together?

Find the number of permutations of n things, taken r at a time, in which 3 particular things : (i) always occur (ii) will never occur.

The no.of all permutation of n distinct things taken all at a time is n!