Today you were invited for Christmas party write a diary and about 100 to 150 words of party

If 20 persons were invited for a party, in how many ways can they and the host be seated at a circular table? In how many of these ways will two particular persons be seated on either side of the host?

Your friend has not invited you to his marriage party. You will

10 persons are invited for a party In how many ways can they and the host be seated at a circular table?