Question

In how many ways can one arrange the letters in CORRESPONDENTS so that a) there is no pair of consecutive identical letters b) there are exactly two pairs of consecutive identical letters c)there are at least three pairs of consecutive identical letters?

Answer 1

14 letters in the werd, so 14 waes tu pik letter 1

13 waes tu pik letter 2,

12 waes tu pik letter 3,..

anser=13!=6,227,020,800

Answer 2

14!=87,178,291,200