Travis has 6 engineering books to line up on a shelf. kelly has 4 finance books to line up on a shelf. if all the books are different, in how many more orders can travis line up his books than kelly?

The number of ways 6 different objects can be arranged in a row is given by 6! = 6 x 5 x 4 x 3 x 2 x 1 = 720

The number of ways 4 different objects can be arranged in a row is given by 4! = 4 x 3 x 2 x 1 = 24

Therefore, the number of ways which Travis can order his books more than that of Kelly is given by 720 - 24 = 696.