Dan Croker has two obsessions - Sudoku and frogs. So he just had to combine his loves and make the Famous Frog Sudoku books. The Bathroom Sudoku Series Book 9 contains 500 very hard puzzles with 4 puzzles per page. Featuring a fun and colorful cover that is sure to brighten your day. Of course, you don't have to be in the bathroom to do these puzzles! Solutions are given at the end of the book. Look out for many more Famous Frog Sudoku books.