- Read call numbers line by line, from left to right and from top to bottom. (Note that the same call number can be written from top-to-bottom, or left-to-right as shown in the picture.)
- Read call numbers numerically. Numbers in front of the decimal are read as whole numbers and numbers following a decimal are read as decimals.
- Following the number, read the letters in alphabetical order.
Every Dewey Decimal call number begins with three numbers, some with decimal numbers, followed by various letters and/or number combinations.
- Numbers to the left of the decimal point are whole numbers. Therefore, 813 comes before 8.13.04.
- Numbers to the right of the decimal point are decimal numbers. Therefore, 813.87 comes before 813.885.
