What is a Permutation?
A permutation is an ordered arrangement where r objects are chosen from n different distinct objects, and repitition is not allowed. nPr represents the number of permutations of r objects selected from n objects.1 The formula seeks to solve the number of permuatations of n distinct objects taken r at a time, where:
1. the n objects are distinct
2. once an object is used it cannot be repeated
3. order is important
It's important to note that n is the set or total population being evaluated and r is a subset of n.
Permutation Video Tutorial
The following video provides an easy to understand overview of how to calculate permutations and combinations.
1. Statistics Informed Decisions, 2nd Edition, Michael Sullivan.