# Permutation: Circular

How to solve a circular permutation: formula, 1 example, and its solution.

## Formula

The number of ways

to arrange n things in a circle is

(n - 1)!.

This is the circular permutation formula.

## Example5 Students, Round Table

Solution

Solution (Detail)

There are 5 students.

They are sitting at a round table.

This is arranging 5 students

in a circle.

So the number of the ways is,

5 - 1,

4!.

4! = 4⋅3⋅2⋅1

Factorial

4⋅3 = 12

2⋅1 = 2

12⋅2 = 24

So the answer is 24.