Question

A round table conference is to be held between delegates of 20 cuntries. In how many ways can they can they be seated if two particular delegates may wish to sit together?

Answer 1

Regarding these two delegates as one, the 19 delegates can be arranged at a circular table in 18 ! Ways.
These two delegates can be arranged among themselves in 2 !, i.e., 2 ways.
`therefore " the required number of ways "=2 xx(18!).`