I believe you are asking in how many ways they can sit. If so:
The 1st can sit anywhere: he has only 1 way to sit
The 2nd can sit in 11 ways, since one seat is already occupied
The 3rd can sit in 10 ways, since 2 seat are already occupied
The 4th can sit in 9 ways, since 3 seat are already occupied
The 5th can sit in 8 ways, since 4 seat are already occupied
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The 12th can sit in 1 way, since11 seat are already occupied
General formula for a circular table:
Number of ways they n persons can be seated: (n-1)!
and the 12 can be seated in (12-1)! = 11! = 39,916,800 ways.
This is called circular permutation