Dan Croker has two obsessions - Sudoku and frogs. So he just had to combine his loves and make the Famous Frog Sudoku books. The Brain Yoga Series Book 8 contains 500 very hard puzzles with 4 puzzles per page. With a fun and cheery cover that is sure to brighten your day. Solutions are given at the end of the book. Look out for many more Famous Frog Sudoku books!