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How to Read a Dewey Call Number

The Dewey Decimal Classification uses numerals to represent subjects. The hundreds digit represents a large disciplinary grouping, the tens digit represents a field within that discipline, the one's digit represents a aspect of that field, and so forth. For instance, the 300's are the Social Sciences, the 370's cover Education, and 378 is Higher Education.

Dewey Decimal call numbers are used in several UNB WorldCat locations, among which are HIL-AV4, HIL-BBKRM, HIL-CLC, HIL-JUV, and HIL-SPECCL. There are some variations among the call number formats used in these locations, but the basic structure remains the same in all Dewey Decimal call numbers.

Here is an example of a Dewey Decimal call number as it appears in a UNB WorldCat record:

915.694 B516

On the book spine this call number appears as:


The first line is treated as a unit and files in numeric sequence, with 915.5 preceding 915.694, which precedes 915.72. The second line is treated identically to the line in a Library of Congress call number, which consists of a letter followed by one or more numerals. The shelf sequence is determined one character at a time, B51 precedes B516, which precedes B52.