Why the repetetive use of the number "7" in the Bible? Why do biblical authors continually use the numbers "3" or "12" to describe certain things? Robert D. Johnston created a book, a very small book, which answers some of the questions behind the use of certain common numbers in the Bible. If you're a Biblical scholar, you may want something meatier like "Spice of Torah" by Locks or perhaps "Biblical Numerology" by John J. Davis. However, I must admit that this book is quite handy when a quick answer is needed.