Fastest way I could find.
Load up a easy suduko challenge from the challenges menu.
There are 3 of these a day so should be easy to find an easy suduko one.
These are usually complete 3 rows or columns.
Now fill ever square with 1 to 9 of notes.
Now complete the puzzle for the notes to count towards your total.
Potential to do around 450 notes in one game.
Solution will also unlock :