During my research on the competition for Lichtenbergianism: procrastination as a creative strategy, I found myself over at the Library of Congress catalog checking out the Cataloging-in-Publication Data (CIP) for The Art of Procrastination.

First of all, if I may rant a bit, why isn’t CIP actually in the actual freaking publication anymore??  It used to nestle on the copyright page of new books, and a blessing it was, too, to those of us who had to enter cataloging by hand now and then.

This is not to say that it was always accurate.  The LOC catalogers who provided this information to publishers often had to work only from a title page, and sometimes their subject headings (and subsequent call numbers) were hysterically off.  But still, it was nice to have.

I presume that the speed with which books hit the market these days has made it impossible for even a cursory amount of pre-publication cataloging, so now we’re stuck with a kind of patent pending note in the front of our books: “Library of Congress Cataloging-in-Publication Data is available.”  It’s also probably true that only in the wilds of the Amazon—or maybe west Texas—are there libraries without access to electronic cataloging.  Still, I would like to go on the record as offering my services to any and all publishers to do their CIP data in-house.  For a respectable fee, of course.

Anyway.

I chose to find The Art of Procrastination through its ISBN number.  That stands for International Standard Book Number, and it’s exactly what it sounds like.  The ISBN number used to be ten digits long; now it’s thirteen, because they were running out of ten-digit numbers.  (Kind of like IP addresses on the intertubes.)

Like all the other numbers that tag things in our lives—UPC numbers, etc.—the part of the ISBN number that actually identifies the book is just the first twelve digits.  The last number is a checksum, a number that is calculated from the the other digits.  When you put an ISBN number into a system that cares about these things, it will do that calculation to see if it comes up with correct checksum.  If it doesn’t, it flags the number as incorrect.  In other words, the checksum calculation is meant to snag incorrect digits or transposed digits.

If you are of an inquiring mind like I am, a simple question has nagged at you for years: how does that work even??

Today, I learned.  Here, go look.  (It’s not hard.)

There are different checksum algorithms for different systems, but essentially they work the same way: multiply the digits with alternating prime numbers, add them up, subtract them from the nearest multiple of ten.

I can continue my slow march to the grave with one less puzzle of life gnawing at my soul.