2.  The dewey decimal system works like this there is a call number and it has two parts the DDS and the cutter number. The DDS comes first and then the cutter number to make a unique number.  Why this is because some books may have the same DDS number so they stick a letter on the end of the DDs which is the cutter #

3.  There is 10 main categories for the dewey decimal system.  In these categories there are even more sub- categories  So the more numbers the more specific it gets

4.  The cutter # for a book has the authors 1 st letter of their last name before the series of random numbers and the first letter of the books title.

5.  Like the harry potter book chamber of secrets the DDC # would be 823.914.But all of the harry potter books have the same DDC#. So they would add the cutter # which would be R797c.