Boost your brainpower--and have fun!--with 90 days of easy-to-hard sudoku puzzles. Are you craving a mental challenge, looking to ward off brain fog, or just seeking a fun way to energize your mind in the morning? Take the Sudoku for Brain Fitness challenge and train your brain with 90 days of sudoku puzzles that progress from easy to hard--all while having fun! With expert tips on improving your sudoku-solving skills and bonus puzzles to keep your good habit going, you'll be amazed at the improvement in your focus, memory, and problem-solving skills in just three short months. 90 days of sudoku--and another month of bonus puzzles. Top-quality puzzles crafted by sudoku experts, not a computer. Helpful sudoku-solving techniques and tips. From cross-hatching to X-wing, the expert authors explain top strategies to help you become a sudoku master. Large, clear text. Avoid eye strain with the easy-to-read text.Big grids and margin space. Plenty of room to jot down notes. Answer key in the back. So you can easily check your answers.Great gift for puzzle lovers. Perfect for travel or just unwinding at home.