Within the first Book of Chronicles at chapter twenty-one and verse one; we are told that satan instigated, allured, enticed King David to number Israel. In like manner, it appears that satan instigated, allured, enticed someone to number the Bible.
The Bible is not one book but rather one volume; a collection of 66 books and letters written by 40 authors.
Thus, the volume is divided into books and this is perfectly understandable.