Open the book to the title page. Located a few pages into the book, the title page contains the title, the author, and sometimes some copyright information. There may be more than one page with the book title on it, but the title page is the one you want.
Turn the title page to find the copyright page on the back, or “verso,” . This page contains the copyright date, publisher information, International Standard Book Number (ISBN), and the Library of Congress Cataloging-in-Publication data (CIP).
Find the CIP information, which begins about halfway down the page. It may be marked “Library of Congress Cataloging-in-Publication Data.” The CIP contains information such as the book’s title, author, subject headings, and the DDC number.
Find the Dewey decimal number. This number will usually have three digits followed by a decimal point, then more digits. For example: “373.7.” Sometimes, the number will look like this “373.7’220973." The apostrophe (‘) symbolizes where a librarian can cut off the number so that it will fit on the spine of a book.