The number of possible ways to choose permutations from total items is denoted using two parentheses with the variables and . A subscript is included to indicate that the expression represents permutations where order does matter as opposed to combinations where order does not matter. Typically, the notation is used in an expression like this:
In plain language, this represents the total number of permutations from choosing items from a collection of items. See combinations for where order does not matter.
The permutation formula describes the possible permutations of r elements out of a group of n elements where order does matter.