It all depends on how many forms you order. For example, if your order quantity is 50, you will get either 1 book of 50 forms or 2 books of 25 forms. The quantity is not the number of books; it is the number of forms ordered.
Example:
QTY ÷ SETS per Book = Number of Books
1000 Forms ÷ 50 Sets Per Book = 20 Books