What Is a Number Line in a Book? How to Read Printer's Number Lines
The number line — also called the printer’s key, print line, or edition line — is a row of numbers on the copyright page of a book that identifies which printing (or impression) the book represents. It is the most common method used by modern publishers to indicate printing history, and reading it is the most fundamental skill in first edition identification. If you can read a number line, you can identify a first printing from most major publishers.
How Number Lines Work
The basic principle is simple: the lowest number present in the line indicates the printing. For each new printing, the publisher removes the lowest number.
Standard Format
A typical number line looks like this:
First printing: 1 3 5 7 9 10 8 6 4 2
Second printing: 3 5 7 9 10 8 6 4 2 (the “1” has been removed)
Third printing: 3 5 7 9 10 8 6 4 (the “2” has also been removed)
The numbers are typically arranged so that the odd numbers count up from the left and the even numbers count down from the right, meeting in the middle. This arrangement allows the printer to remove numbers from both ends of the line, keeping the line centered.
Variations
Not all number lines follow the standard format. Common variations include:
Sequential: 1 2 3 4 5 6 7 8 9 10
In this format, the lowest number is still the indicator, and numbers are removed from the left for each new printing.
Reversed: 10 9 8 7 6 5 4 3 2 1
Numbers are removed from the right. If the “1” is present, it is a first printing.
With publisher name or year: 1 3 5 7 9 10 8 6 4 2 / Random House
Some publishers include their name or a date code alongside the number sequence.
Year and printing combined: 1 2 3 4 5 06 07 08 09 10
The higher numbers represent years. This format tells you both the printing number and the approximate year of that printing.
Publisher-Specific Practices
Random House / Alfred A. Knopf / Vintage
Uses the standard 1 3 5 7 9 10 8 6 4 2 format. A “1” present in the line indicates first printing. Additionally, Knopf books often state “FIRST EDITION” on the copyright page, which is removed from later printings.
Simon & Schuster
Uses a standard number line. First printings typically show “1” as the lowest number. Some imprints also include the words “First Edition” alongside the number line.
HarperCollins / Harper & Row
Uses a standard number line. First printings are identified by the presence of “1” in the line. The words “FIRST EDITION” are usually present on the copyright page of first printings and removed from subsequent printings.
Penguin Random House Imprints
Most Penguin Random House imprints (Doubleday, Crown, Dutton, Viking, G.P. Putnam’s Sons, etc.) use standard number lines. The “1” indicates first printing.
Houghton Mifflin / Houghton Mifflin Harcourt
Uses a standard number line. First printings include “1” in the sequence.
Farrar, Straus and Giroux
Uses a standard number line. First printings are identified by the presence of “1.”
Scribner’s (Modern)
Uses a standard number line with “1” indicating first printing. Historically, Scribner’s used an “A” on the copyright page to designate first printings (the famous “A” associated with Hemingway and Fitzgerald first editions).
Little, Brown and Company
Uses a standard number line. First printings show “1” as the lowest number. The words “First Edition” are usually present.
Oxford University Press / Cambridge University Press
Academic publishers may use number lines but often use edition statements instead: “First published 2024” or “First edition.”
Historical Methods (Before Number Lines)
Number lines became standard in the 1970s. Before that, publishers used various methods to indicate printing history:
Edition Statements
Many publishers simply printed “First Edition,” “First Printing,” or “First Published [date]” on the copyright page. The statement was removed or changed for subsequent printings.
Example: Scribner’s classic method used the letter “A” on the copyright page of first printings. For the second printing, “A” was removed and replaced with “B.”
No Indication
Many publishers before the mid-20th century provided no printing indication at all. The copyright page might show only the copyright date and the publisher’s name. Identifying first printings of these books requires knowledge of specific issue points — details of binding, dust jacket, or text that distinguish the first printing from later ones.
Date-Based Methods
Some publishers indicated printings by showing the dates of all printings on the copyright page:
First printing, October 1960
Second printing, November 1960
Third printing, December 1960A first printing would show only the first date with no subsequent printing dates listed.
Common Mistakes in Reading Number Lines
Confusing Edition and Printing
A “first edition” and a “first printing” are not technically the same thing, though in collecting parlance they are often used interchangeably. The “first edition” is the first publication of the work; the “first printing” is the first impression of that edition. A book can be a “second printing of the first edition” — still the first edition, but not the first printing.
For collectors, “first edition” almost always means “first printing of the first edition.” This is what the number line identifies.
Misreading the Lowest Number
The key number is the lowest number present, not the first or last number in the sequence. In 1 3 5 7 9 10 8 6 4 2, the relevant number is “1” — not “10” or “2.”
Ignoring the Number Line
Some buyers rely on the words “First Edition” on the copyright page without checking the number line. This can be misleading because some publishers leave “First Edition” on subsequent printings while removing the “1” from the number line. If the words say “First Edition” but the number line starts at “3,” you have a third printing.
Book Club Editions
Book club editions (BCEs) may have number lines that appear to indicate a first printing — but the book is not a first trade edition. BCEs are identified by other features: absence of a price on the dust jacket flap, a blind stamp on the rear board, different binding cloth or paper, and often a smaller physical size.
Why Number Lines Matter
The number line is the quickest and most reliable method of determining whether a modern book is a first printing. A first printing of a collectible book may be worth 10–100x more than a second or later printing. Learning to read number lines takes minutes; the knowledge pays dividends for a lifetime of collecting.
When evaluating a book, always check the number line first, even before looking at the condition or dust jacket. There is no point in carefully assessing the condition of a third printing.