- 250 exciting, exciting puzzles - Hidoku-Doku 15 x 15 Very hard + SuCroCuroDoku 13 x 13 + Numbriks 15 x 15 Very hard + Killer Sudoku 12 x 12 "X" Diagonal Very hard + Classic Sudoku 15 x 15 Very Hard.- the very hard version as a champion, the golden prize of extreme Sudoku - each Sudoku has a unique solution - tasks are conveniently located - large font - develops memory, logical thinking, helps to focus - 2 puzzles on the page - wide internal fields allow you to record your decisions and thoughts- very convenient and practical - expands creative possibilities - perfect gift for all fans of puzzles. An excellent book for free time pastime and mind training. I hope you enjoy my book. I would also be very grateful if you could write a review. Thank you. Best regards, Andrii Pitenko