Given that the front circle of this book states "Hard", I expected this book to fall between the "Hard" book of Brown Belt Kakuro and the "Super Tough" book of Black Belt Kakuro from this series, both of which I love. I can complete at least 90% of the Black Belt puzzles without making a math error or getting stuck, but this book appears to be full of dead-end puzzles. You will feel like you are making progress, and all the numbers are starting to fall into place, and then you will be stuck again. That happens a few times in the Black Belt series per puzzle - and you can figure it out. In this book it seems like there are 10-20 "I'm stuck and can't figure out what else to do" moments. There have been times I've been able to complete a puzzle without any cheating, but they are too few for me to truly enjoy the book. I will be ordering another set of the Brown and Black Belt books again and putting this one off to the side.