- 250 best puzzles + surprise in 250 killer sudoku very hard (need to download and print)- Sudoku 15x15, separated by smaller rectangles of 5x3 cells. It is necessary to fill empty cells with numbers from 1 to 15, each of the digits should appear only once in each line of the 15x15 square, 15x15 column and 5x3 rectangle- levels continue to please. 50 Easy + 50 Medium + 50 Hard + 100 Very hard- all riddles have only one verified solution- 2 puzzles on 1 page, very practical and convenient- a lot of free space for the progress of your thoughts- good mind support in excellent form- large font- develops memory, logical thinking, helps to focus- creative possibilities are expandingIdeal gift for all fans of puzzles. An excellent book for free time and learning of the mind. I hope you enjoy the book. I would be very grateful if you write a review.Best regards,Andrii Pitenko