In math, we write a permutation like this:
In plain language, this represents the number of possible permutations when you choose elements from a collection of elements. The subscript indicates that the expression represents a permutation where order matter’s. See the combination notation for when order does not matter.
In general, to express choose permutations we write:
To calculate the number of permutations see this formula.
The number of possible ways to choose r combinations from n total items is denoted using two parentheses with the n value above the r value. A subscript p or c is used to denote whether it is a combination or permutation.