they don't
400-499
The library uses the Dewey Decimal Classification system to allocate numbers to books.
Books on philosophy are typically assigned the numbers 100-199 in the Dewey Decimal Classification system.
I believe that you are thinking of the Dewey Decimal System.
The Dewey Decimal Classification (DDC), or Dewey Decimal System, is a proprietary library classification system first published in the United States by Melvil Dewey in 1876.
Dewey Decimal is the classification system of the library.
The Dewey Decimal System places topics related to religion in the 200s section. This includes books on Christianity, Islam, Judaism, and other world religions. Each religion is assigned a specific range of numbers within the 200s to organize related topics.
It's called the Dewey-decimal system.
know the ten main devesions of the Dewey decimal system
Astronomy is in the 520 section of the Dewey Decimal System.
Melville Dewey
The system used most extensively is the Dewey Decimal Classification or DDC, also called the Dewey Decimal System. It was developed, in its original form by Melvil Dewey in the mid 1870's Scitech