Keep Your Brain Young: 512 Sudoku Puzzles - Simple, Easy, Intermediate, and Expert With Answers - Book 84 A worthy collection of 51200 Sudoku puzzles in 100 books (each book contains 512 grids together with relevant solutions) 512 Sudoku puzzles and solutions with 4 difficulty levels Puzzles for everyone with different Sudoku solving skills(for kids and adults) 4 difficulty levels: 128 Simple, 128 Easy, 128 Intermediate, and 128 Expert Sudoku puzzles solving is a good prevention method for Alzheimer's and Dementia. Keep your brain young with logic-based number placement puzzle Sudoku is an easy to learn logic-based number placement puzzle and very popular all around the world. It is indeed a game for all ages: from kids in preschool to grown-ups. It is possible to form and solve a Sudoku puzzle with letters or even some symbols. A classic Sudoku puzzle is an 81-cell square grid made up of 3 x 3 subgrids or 9 smaller blocks, also known as regions and boxes. Some cells already include numbers (called as givens). The game aims to fill all the blank cells with one digit from 1 to 9 in such a way without ever repeating a single one in the same row or the same column, or in the same block to solve it correctly. Because the word Sudoku is the abbreviation of a Japanese expression: suji wa dokushin ni kagiru (Su means digit and doku means single. Thus, every number must be unique). On the other hand, you must use all of nine set of 1 to 9 digits to solve it correctly. Every invalid puzzle has more than a single and unique solution. This book contains 512 puzzles in 4 levels of difficulty levels: simple, easy, intermediate, and expert with solutions. Each level has 128 grids. We also have designed 100 books including 51200 puzzles. As, the puzzles with large size is easy to use, each page consists of only two grids. Also, each grid has some useful information such as the given numbers and difficulty degree. The difficulty of a grid is wholly related to some details including the number of givens and also the rules that a solver may apply to complete it. We have estimated it based on weighted parameters such as the number of givens, Singles, hidden singles, naked pairs, hidden pairs, pointing pairs/triples, box/line intersections, guesses, and backtracks. Have fun and enjoy!Gholamreza Zare ([email protected])Pegah Malekpour Alamdari ([email protected])