A librarian has a set of nine books, including four different books about Abraham Lincoln. The librarian wants to put the nine books on a shelf with the four Lincoln books next to each other, somewhere on the shelf among the other five books. How many different arrangements of the nine books are possible?  Pick one.
A) (9!)/(4!)
B) (4!)(5!)
C) (4!)(6!)
D) (4!)(9!)
E) (4!)(5!)(9!)
You can club the four Lincoln books as one, which leaves us with five other books plus this one to think about. So, these six items can be arranged in 6! ways, and since the four books can be moved around among themselves with each combination giving us a new overall combination, we have an additional 4! ways. Therefore, the answer would be 6!*4!, which is (4!)(6!).
<result>C</result>
A librarian has a set of nine books, including four different books about Abraham Lincoln. The librarian wants to put the nine books on a shelf with the four Lincoln books next to each other, somewhere on the shelf among the other five books. How many different arrangements of the nine books are possible?