The 10-Letter Secret Behind Every Antique Price Tag
Here's a puzzle hiding in plain sight. When you pick up an old book at an antiquarian fair and flip it open, you might find a penciled code inside the front cover. Something like BU or RKT. Not a word. Not a price. A secret.
Welcome to price codes: the substitution cipher that booksellers have used to hide what they actually paid for something, right there in the open, for anyone not to read.
How Price Codes Work
A price code is elegantly simple. You pick a word or phrase where every letter is different. No repeats. Each letter stands for a digit, 1 through 9 (or 1 through 10 if you need all ten).
Take MONEY TALKS. That's M=1, O=2, N=3, E=4, Y=5, T=6, A=7, L=8, K=9, S=0. Now if a dealer paid $85 for a book, they write LY inside. You see LY. They see $85.
The rule is strict: no repeated letters. That's what makes this a real constraint puzzle. You can't use MISSISSIPPI. You can't use BANANA. You need something where every character shows up exactly once.
The Words People Actually Choose
This is where it gets fun. The examples catalogued in Ian Jackson's book on the subject include some inspired choices. ROSENTHAL. TUXEDO PARK. INTROUVABLE. MY GOD HELPS. BANKRUPTCY.
And then the two that end up in the title: CHAMBERPOT. MOTHERFUCK.
Check those last two. Count the letters. No repeats in either one. Ten letters each. Perfect ciphers. Jackson published the book under the pseudonym Exhumation, and the title, "Chamberpot & Motherfuck: The Price-Codes of the Book Trade," is itself a demonstration of the concept. The profanity is the point: memorable, unique, and technically flawless for the job.
This Is Older Than You Think
The OED's entry for "price code" only dates to 2007, but the practice is much older. The earliest citation the OED found is from the Chicago Tribune in 1905. Two years later, in 1907, the Tribune was explaining that price codes are "most frequently arranged on a word of nine or ten letters."
Nine or ten non-repeating letters. Which is why BANKRUPTCY works so well. Count them: B-A-N-K-R-U-P-T-C-Y. Ten letters. Zero repeats. One perfect cipher.
A Secret the Reference Books Missed
Here's something worth noting. Roger Stoddard's "Marks in Books" from 1985, a standard reference on what you find written inside old volumes, doesn't cover price codes at all. David Pearson's "Provenance Research in Book History" from 1994 doesn't venture beyond the seventeenth century on the subject.
Which means for a long time, there was no serious catalogue of what codes actually existed. Jackson's second edition documents 226 codes, plus 18 more in an Addenda sheet. That's 244 total. Twice as many as his earlier 2010 edition. A whole hidden language, finally mapped.
Why Word People Should Care
Price codes are basically a word game with real stakes. Every dealer who wanted their own cipher had to solve a constraint puzzle: find a meaningful word or phrase where every letter shows up exactly once. That's not easy. It's the same challenge you get in certain word puzzles, except the reward is keeping your margins secret from browsers.
The people choosing these words weren't picking randomly. They were word people, choosing with care and a little flair. MONEY TALKS and MY GOD HELPS both do the job and make a point. BANKRUPTCY is bleak but functional. MOTHERFUCK is unforgettable. Which is rather the idea when you need to remember your cipher mid-transaction.
Try Making Your Own
See if you can construct a valid price code. The rules: 9 or 10 letters, every letter unique, no repeats anywhere.
BLACKOUTS? B-L-A-C-K-O-U-T-S. Nine letters, none repeated. Valid cipher.
THUMBTACK? T-H-U-M-B-T-A-C-K. Two T's. Disqualified.
The constraint is tighter than it looks. English has a lot of words with repeated letters. Finding a long one with all unique letters is a genuine puzzle, which is exactly the point of a cipher meant to be hard to crack by accident.
The booksellers knew what they were doing. They just didn't know they were playing a word game the whole time.
Source: Languagehat