Circular Permutations Calculator
Calculate circular permutations - arrangements around a circle where rotations are identical. Includes necklace problem (reflections) and visual ring diagrams.
(n-1)!Results
Circular Permutations
24
(5-1)!
Input Values
People, beads, or items to arrange in a circle
Use (n-1)!/2 when clockwise = counterclockwise
Results
Circular Permutations
24
(n-1)! = (5-1)!
Rotations identical, reflections different
Necklace (with reflections)
12
(n-1)!/2
Both rotations and reflections identical
Linear Permutations
120
n! = 5!
Standard arrangements in a line
Comparison: Linear (120) = 5 x Circular (24). Each circular arrangement corresponds to 5 linear arrangements (all rotations).
Visual Ring Diagram
Position A is fixed as reference. The remaining 4 positions can be arranged in 24 ways.
Step-by-Step Calculation
Circular Permutations
Necklace Permutations
Why (n-1)! Instead of n!?
In a line, positions are absolute: ABCD is different from BCDA.
In a circle, positions are relative. If everyone moves one seat clockwise, the arrangement looks identical:
ABCD = BCDA = CDAB = DABC (all rotations of the same arrangement)
There are n rotations of each circular arrangement, so we divide linear permutations by n:
Circular = n! / n = (n-1)!
Equivalently, we fix one person's position (as a reference) and arrange the remaining (n-1) people.
Practical Examples
When to Use Each Formula
Use (n-1)!
When clockwise differs from counterclockwise:
- - People at a round table (can tell left from right)
- - Circular race track (direction matters)
- - Clock face arrangements
- - Spinning wheel segments (direction matters)
Use (n-1)!/2
When clockwise equals counterclockwise:
- - Necklaces and bracelets (can flip)
- - Keyrings (no top/bottom)
- - Circular logos (can be viewed from either side)
- - Physical rings with no orientation
Permutation Formulas Comparison
| Type | Formula | For n=5 | Description |
|---|---|---|---|
| Linear | n! | 120 | Arrangements in a line |
| Circular | (n-1)! | 24 | Rotations identical |
| Necklace | (n-1)!/2 | 12 | Rotations + reflections identical |
Results
Circular
24
(5-1)!
?How Do You Calculate Circular Permutations?
Circular permutations count arrangements around a circle where rotations are considered identical. Formula: (n-1)! for n objects. Example: Seating 5 people around a round table = (5-1)! = 4! = 24 ways. For necklaces where flipping is also identical (clockwise = counterclockwise), divide by 2: (n-1)!/2.
What are Circular Permutations?
Circular permutations count the number of ways to arrange n distinct objects in a circle where rotations are considered identical. The formula (n-1)! comes from fixing one object's position (eliminating rotational equivalence) and arranging the remaining n-1 objects. For problems like necklaces or bracelets where flipping also produces equivalent arrangements, divide by 2 to get (n-1)!/2.
Key Facts
- Circular permutations formula: (n-1)! for n distinct objects
- In circular arrangements, rotations are considered the same
- Linear permutations: n! vs Circular: (n-1)! - factor of n difference
- Necklace/bracelet problem: (n-1)!/2 (reflections also identical)
- 5 people at round table: (5-1)! = 24 arrangements
- One position is fixed as reference, others arranged around it
- Used for: seating charts, round tables, clock faces, rings
- If clockwise different from counterclockwise, use (n-1)!; if same, use (n-1)!/2
Quick Answer
Circular permutations count arrangements around a circle where rotations are considered identical. Formula: (n-1)! for n objects. Example: Seating 5 people around a round table = (5-1)! = 4! = 24 ways. For necklaces where flipping is also identical (clockwise = counterclockwise), divide by 2: (n-1)!/2.
Frequently Asked Questions
Circular permutations count arrangements around a circle where rotations are considered the same. For example, seating A-B-C-D around a table is the same as B-C-D-A (rotated). Formula: (n-1)! for n objects.
In linear arrangements (n!), position matters absolutely. In circles, rotating everyone gives the same arrangement. We fix one person as a reference point and arrange the remaining (n-1) people, giving (n-1)! arrangements.
The necklace (or bracelet) problem considers arrangements where BOTH rotations AND reflections are identical. A necklace looks the same if flipped. Formula: (n-1)!/2 for n distinct beads.
Use (n-1)! when clockwise and counterclockwise are different (e.g., people at a table - they can tell left from right). Use (n-1)!/2 when they are the same (e.g., beads on a necklace - can flip the necklace).
For n people at a round table where clockwise differs from counterclockwise: (n-1)! arrangements. Example: 6 people = 5! = 120 ways. If the table can be rotated and there is no "head", we fix one person and arrange the rest.
Last updated: 2025-01-15
Results
Circular Permutations
24
(5-1)!