Open the book to the backside of the title page. On the opposite side of the title page, you will usually find the Dewey Decimal Classification number. This will usually be found towards the bottom of the page. It is a three-digit number followed by a decimal point and up to six additional digts, then a dash and an alphanumeric code consisting of "dc" and two more digits.
Familiarize yourself with the 10 general classes that the Dewey Decimal Classification numbers follow. The class categories are "000" for generalities, "100" for philosophy and psychology, "200" for religion, "300" for social science, "400" for language, "500" for natural science and mathematics, "600" for technology, "700" for arts, "800" for literature and "900" for geography and history. Refer to the resources section for a more extensive definition of these classes.
Place the number on the spine of the book. It should be towards the bottom, approximately a half inch from the bottom. If you cannot fit the label on the spine, place the label on the bottom, left-hand corner of the front of the book.
Organize your collection in order by number. If you have two numbers that are the same, such as two books from the same author, arrange them alphabetically by title.