Sudoku puzzles are great to keep the mind sharp. What are some benefits of working on Sudoku challenges? It boosts logical thinking and decision skills; it can help memory, math and recall; some studies show it can help slow the negative impacts of Alzheimer's; it can help with concentration. 200 puzzles at the hard or advanced level are found in this book - with solutions included. The large size book makes it easy to work the puzzles. Enjoy!