What could be left to classify after nine weeks? This is the section that covers all the gaps, called the Generalities, 000s.
You may be curious why there are no books in the some number ranges. When Dewey began his system, 140 years ago, he knew he might miss some fields at his library that might hold many shelves at another library. So he left several sets of numbers empty. Many have filled in the past decades, but several remain unassigned. For a complete listing of which numbers are still blank and exactly what topic fits in what number, check out the list at Wikipedia.
In addition, each library has some discretion as to where to classify a book or where to display them. For example, biographies may be found in 921-928 or in 040s, but Ruidoso Public Library consolidates all biographies on one wall with the number "92" on the spine label, then the subject's last name.