Q5 of 140 Page 317

In how many differents ways can 20 different pearls be arranged to form a necklace?

We know that necklace in the form of a circle, So we need to arrange 20 pearls in Circle

20 pearls can be arranged by 19!


Now each pearl have the same neighbours in the clockwise and anticlockwise arrangement


Total number of arrangement are (19!)/2


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