Permutation

 

The number of ways to arrange items from a set is called a permutation. The formula for calculating permutations is P(n, r) = n!/(n-r)!, where n is the total number of items and r is the number of items selected. This formula uses factorials, and we'll practice calculating permutations using this formula.

How to compute the number of permutations for a given set of objects

To compute the number of permutations for a given set of objects, you can use the formula:

nPr = n!/(n-r)!

where n is the total number of objects, r is the number of objects to arrange, and ! denotes factorial. For example, if you want to arrange 3 objects from a set of 4, you calculate:

4P3 = 4!/(4-3)! = 4!/1! = 24

This formula accounts for the order of arrangement, making it suitable for scenarios where the sequence matters.