Sudoku for Beginners 240 Ultra Easy Puzzles to MasterPaperback, 20 September 2017

If you want to increase your concentration power, then you chose the right book to do that. Sudoku is a numbers game that requires memory and logic. You have to think strategically and creatively to solve the puzzles. Whenever you stop in the middle of the game, you restart your thinking process and that improves your re-focus skills and concentration power. Good luck!