What is the useful site could we get the call numbers of books faster?

If your cataloging books you can copy catalog through z39.50..or in livrary of congress websitesbor if you are just a plain user you can access the livrary OPAC of certain institution

OCLC classify

check this site you can search by author, keyword or title.

My top two preferences:

Library of Congress Online Catalog: https://catalog.loc.gov

OCLC WorldCat: https://www.worldcat.org/

 

 

serial nos and your cataloging system is the best way to find your books.

Cataloging system 

A useful site which could get you call number of books faster is usually The Library's Research Help Page or the Resources for Undergraduates Page or Graduates Page which ever one you prefer.

For Library User Visit the Library Catalogue (OPAC). For professionals, there are lots of  Sites for example. www.chopac.org (free), Classify.oclc.oeg (Free), Classificationweb.net (Subscription ) etc..

online public access catalogue system.

Library of Congress: http://catalog.loc.gov

OCLC WorldCat: http://www.worldcat.org

OCLC CLASSIFY for class number and CATALOGUING CALCULATOR for cutter number.

 

 

 to dewy classification DDC cuter number