Tuesday, July 31, 2007

Secrets of the Illuminati

In the Comment trail, the estimable Ms. Faye L. Booth notes that, on her ISBN-10, the last three digits, including the check digit, are 666: 0-230-529666. So now we have a clue what the "L" stands for. (Faye Lillith Booth? Faye Lucifera Booth?)

Her ISBN-13 lacks this quality: 978-0-230-52966-3. Just to make sure the ending wasn't another 6, I did the 1, 3, 1, 3... multiplication (see previous post), and 978-023052966 multiplies out and sums to 117. Sure enough, the next multiple of 10 from 117 is 120, and 120 - 117 is 3--the value of the check digit.

Crazed with success, I applied the same logic to her ISBN-10, expecting to come up with 6. Instead, in a moment worthy of a supernatural thriller, I arrived at 7.

As it turns out, the old ISBN-10 uses an even sillier system than multiplying by 1 and then 3 and then 1 and then 3... ISBN-10 gets its check digit by multiplying by the declining sequence 10, 9, 8, 7, 6, 5, 4, 3, 2. So, using the first nine digits of Faye's ISBN-10 (0-230-52966):

0 x 10 + 2 x 9 + 3 x 8 + 0 x 7 + 5 x 6 + 2 x 5 + 9 x 4 + 6 x 3 + 6 x 2

= 0 + 18 + 24 + 0 + 30 + 10 + 36 + 18 + 12

= 148

Now it might seem that we would look for the next multiple of 10...but no. The ISBN-10 algorithm looks for the next multiple of 11, which turns out to be 154 (11 x 14). And 154 - 148 = (hold your breath!) 6 --the last digit in Faye's ominous ISBN-10.

Does this multiplying by ones and threes, or by a rocket-countdown from ten, strike you as just a little bit overcomplicated for the task of slapping a barcode on a novel?

I think there's something more sinister lurking here. Either this is some sort of alien language, or the Enlightened World Masters are sending out wisdom from their caves beneath the Himalayas, or the New World Order is issuing commands leading up to the moment of World Domination, or Adolf Hitler's brain is still alive and has been sending out messages from its bell jar in Argentina...

And why the switch from ISBN-10 to ISBN-13? Does this herald the dawning of the New Age, or the End Days, or did someone come perilously close to cracking the ISBN-10 code?

Something fishy is going on. The only question is, do the publishers, or at least some publishers, know? Or are all of them hapless pawns in some grander game?


May said...

What is still mathematically unclear to me is the usage of weights. You can find some more information here:


and here:


Faye L. Booth said...

My brain has just exploded.

(I may not have an official diagnosis of dyscalculia, but I bloody well should have one.)

Faye 'LCF' Booth (yes, I do love The Ninth Gate)

David Isaak said...

If you want to avoid a second brain trauma, do NOT go look at the links May (our resident Math Maven) provided. I did, and I'm still reeling. There are clever little checksums hiding all over the place, with a host of endcoding schemes.

Even in the machine readabe versions of our postal codes. And, even more shocking to me was the discovery that "zip" in our "zip codes" is an acronym rather than a plain-vanilla adjective. It stands for "Zone Improvement Plan."

Now I'm really getting spooked.

may said...

I linked your last two posts to my site, couldn't help it. Should it bother you, let me know and I'll delete everything.

David Isaak said...

Bothered? Not at all. Link any time you like!

Jake said...

I find the mathematics here baffling, but hilarious to read.

I vote for the grander game, by the way.