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Exercise 871Combinatorics › Counting principlesL1Added 3 Nov 2026

Circular arrangements

#circular permutations#necklace#seating

Statement

In how many ways can 66 people sit around a round table (rotations considered the same)?

Hint

Fix one person to break the rotational symmetry; then arrange the rest.

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Solution

Fix one. Place person 11 at a reference seat. The remaining 55 people can be arranged in 5!=1205!=120 ways.

Conclusion. There are 120120 circular arrangements.

Formula. For nn people, (n−1)!(n-1)! circular permutations.