## Everyday Math## Numbers and Math in Everyday Life |

## What is the Dewey Decimal System? |

The Dewey Decimal System of Classification is a numerical method libraries use to classify nonfiction publications into groups based on subject. It was invented by American librarian Melville Louis Kossuth Dewey (1851–1931) as a system for small libraries. The subject of a book is classified by a three-digit numeral that represents ten classes of subjects (000–999). In order, these are Generalities, Philosophy and Psychology, Religion, Social Science, Language, Natural Science and Mathematics, Technology (Applied Sciences), Arts, Literature, and Geography and History. For example, *The Handy Math Answer Book* would be found in the Dewey Decimal System under the 500s for Natural Science and Mathematics.

A Dewey Decimal classification number is followed by the Cutter number, or Cutter. This method was invented by Charles Ammi Cutter (1837–1903) and is an alpha-numeric way to represent words or names by using one or more letters followed by one or more Arabic numerals used decimally. Both systems—the Dewey Decimal System and Cutter—are together called the “call numbers,” a way of locating every book in a library.