Answer:
120960
Step-by-step explanation:
Given that a librarian has a set of ten different books, including four different books about Abraham Lincoln.
The librarian wants to put the ten books on a shelf with the four Lincoln books next to each other, somewhere on the shelf among the other six different books.
First arrnage the 6 other books in the shelf.
This can be done in
Now arrange the 4 books of Lincoln
This can be done in
Now we have 7 places to insert Lincoln books including two corners and in between.
Thus this can be done in 7 ways
Total no of ways =