Identify books in library

Library book code with Dewey decimal system
The number by which a book is identified

Dewey decimal system - books in a library are arranged by subject. These codes can be committed to memory.

Codes

Reference: https://archive.org/details/decimal18v2dewe

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Subject

000

Computer science, information and general work

100

Philosophy and psychology

200

Religion

300

Social Sciences

400

Language

500

Science

600

Technology

700

Art and recreation

800

Literature

900

History and geography