Given, There are 4 books on fairy tales, 5 novels and 3 plays. Here, books are arranged in the order, books on fairy tales, novels and then plays. There are 4 books on fairy tales and they have to be put together. They can be arranged in 4! ways. There are 5 novels. They can be arranged in 5! ways. And there are 3 plays. They can be arranged in 3! ways. So, by the counting principle all of them together can be arranged in 4!´5!´3! ways = 17280