Brain charging. - 100 puzzles Sudoku Calcudoku 9x9 - 25 Easy, 25 Medium, 25 Hard and 25 Very hard. - 100 puzzles Kakuro - 9x9 + 10x10 + 11x11 and 12x12 puzzles.- 100 puzzles Jigsaw Killer Sudoku - 25 Easy, 25 Medium, 25 Hard and 25 Very hard.- 100 puzzles Tridoku Sudoku 9x9 - 25 Easy, 25 Medium, 25 Hard and 25 Very hard. - unique puzzles + 250 sudoku difficult level that can be downloaded and printed. + 250 maze puzzles that can be downloaded and printed. - only 1 verified solution - all answers are at the end of the book - exclusive puzzles - a link to the surprise is at the end of the book. An excellent book for free time and mind exploration. I hope you enjoy the book. Best regards, Basford Holmes