I saw a tattoo the other day that just read 398.2, and I was fascinated. I looked the number up when I got home and it is the Dewey Decimal Library System number at which fairytales begin.
If a library uses the Dewey System, the call number for folklore will be 398, and the numbers from 398.2 up to and including 398.4 will contain most of the fairytale books.