Sudoku, the crossword-like number puzzle, wins more fans every day—and there’s no better sudoku collection for beginners or experienced solvers than this one from puzzle wizard Frank Longo. The rules are simple: Put a number in each square so that each row, column, and 3 x 3 quadrant contains all the numbers from one to nine. But figuring out which number goes in which square calls for serious powers of concentration and logic. The 270 puzzles come in seven levels of difficulty from beginner to expert. As the solver moves up the ladder of difficulty, he or she gets a mental workout like no other—just the thing everyone needs to maintain cognitive fitness!