Library of Congress call numbers should be read one line at a time, as follows:
Line 1: Arrangement of Line 1 is alphabetical.
Line 2: Within the DAs, the arrangement of Line 2 is by whole numbers, as in counting.
Line 3: Within the DA 36s, arrangement of line 3 is first alphabetical, and then numerical; however, the number in line 3 is read as a decimal rather than a whole number.
These rules do not vary. If you apply them and still do not find the material you need, here are some follow-up actions:
[Copied with permission of the University of Richmond Libraries.]