A barcodeOne of the fun things you can do with numbers is create codes. Codes are ways of organizing information in different, useful ways. In one sense, the Fibonacci sequence is a code that nature uses to create the best spacing between things. If you flip over An Elf’s Equations, you’ll find a barcode on the back. Bookstores use barcodes as a quick and easy way for their computers to identify books. And codes can be used to keep information secret and safe.

But a code doesn’t have to be very complicated to work well. Here’s a very simple code that borrows its complexity from other objects. If you and a friend want to send each other secret messages, all you need is two copies of the same edition of a book. Write your message, then look through the book for all the words of the message. Then write down just three numbers to encode the message: the page number, the line number, and the number of the word within that line. For example, the word “Cretacia” appears on page 75, line 5, word 6. Go check it out!

This kind of code is called a book cipher. To make the code even harder to crack, people write the location as just the three numbers. So “Cretacia” above would be (75, 5, 6). The word “Author” appears on page 311, line 1, word 3, or (311, 1, 3).

Got it? Okay, then I have a secret message for you, and you can only decode it if you have a copy of An Elf’s Equations. Ready?

(74, 4, 7) (151, 21, 2) (261, 12, 2) (108, 11, 4) (245, 11, 8): (48, 28, 6) (48, 9, 4) (176, 14, 4) (61, 20, 7) (79, 4, 1) (63, 23, 9) (212, 17, 1) (287, 13, 5) (207, 7, 8) (214, 4, 5)? “(56, 24, 1) (65, 7, 8).”

Did you figure it out? Don’t post it in the comments! Let other people figure it out for themselves. However, feel free to create your own secret messages and post those, either here or on my Facebook post about secret messages. And you can use this method to send secret messages to your friends, as long as you each have an identical copy of the same book. I recommend that you choose a book with a broad vocabulary. That way, you’ll have lots of different words to choose from.

One thing I’m curious about. I actually don’t have an eBook copy of An Elf’s Equations, so I don’t know if the pages, lines, and words fall in the same places. Could someone with an eBook version check? If it turns out to be complete gibberish, go ahead and post it in the comments, just to show how horribly wrong a code can go!

Tomorrow, I’ll be doing a live question and answer session. It’s much easier for me to answer questions if I have them in advance, so please post your questions in the comments either here or on Facebook, and I’ll do my best to answer them. Thanks!