Permutation

The process of selecting things is called as combination and that of arranging things is called as permutation.

A few problems related to the permutations are;

1. Arrangement of books on a shelf.
2. Formation of numbers with the given digits;
3. Formation of words with the given letters.

To find the number of permutations of n object taken r at a time denoted by ⁿP_r. The letter P is an abbreviation of the word ‘permutations’.

P(n,r) = n!/(n-r)!

Permutations will always be a whole number since it is the possible arrangements or counting of numbers. Always equal division of numerator will be given by the denominator.

The variable n refers to the value of total number of objects. The r is the number of actually choosed objects.