Numbers numbers numbers

I found something interesting (especially if you like Chemistry) about arranging the books of the bible in a visual way: https://s3.amazonaws.com/Challies_VisualTheology/BooksoftheBible-2560x1600.jpg

Actually there are a series of diagrams about other Christian topics here: http://www.challies.com/resources/visual-theology-the-books-of-the-bible

Something that I learned in Simply Church Sunday School (we are doing a Old Testament survey), and there  are numerical patterns in terms of events or book arrangements, like for example:

Pentateuch - 5 books
Historical - 12 books
Poetry - 5 books
Major Prophets - 5 books
Minor Prophets - 12 books

The numbers 12 and 5 tend to repeat themselves quite often. Perhaps it means something more, but there is always a danger of over-analyzing. But I think this pattern helps me remember better the order of the books =P.