Permutations

Permutations

Permutation is the technique of permuting or rearranging objects or values in a particular order.

In permutations the order matters, however, in combination the order does not matter.

Permutations are of two types:
1. Where repetition is allowed
2. Where no repetition is allowed

How to calculate permutation with repetition?

If you have n things and n choices each time. And you  have to choose r of them:

The Permutations are as follows: n x n x ........(r times) or n^r

How to calculate permutation without repetition?

In this you have to reduce the number of available choices each time.
Formula: n!/(n-r)!

Where n is the number of things to choose from, and you choose r of them.