Our first- and second-degree Martial Arts Kakuro books were so incredibly popular that we know people are eager for more! So here's the next level of challenge for fans of these addictive conundrums that feature little numbers throughout the grid. Solvers have to fill in the blanks with digits that add up to the little numbers. It's fun, and it stretches your mental muscles, too!

Looking for something hard to test your smarts? These 150 puzzles will give experienced kakuro solvers a great mental workout.