Answer:
The answer is 8! ("eight factorial") = 8*7*6*5*4*3*2*1 = 40320, which is the number of permutations of 8 objects.
(8 ways to put the first book in the first place, then 7 ways to put the second book in the second place, then 6 ways to put the third book in the third place, and so on).