" 10.Find the number of permutations of "10" objects,taken "4" at a time."

Find the number of permutations of 7 objects, taken 3 at a time.

Find the number of permutations of 12 things, taken 6 at a time, in which 3 particular things are : included .

Find the number of permutations of 12 things, taken 6 at a time, in which 3 particular things are : excluded .

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

There are 4n things of which n are alike and the rest different. Find the number of permutations of 4n things taken 2n at a time, each permutation containing the n like things.

Find the number of permutations of 20 things taken 5 at a time so that one particular thing will always occur

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 : will never occur.