Keep your mind young and your memory sharp with 450 Sudoku Variety Puzzles Book. Scientific research has shown that solving logic puzzles as Sudoku keeps your memory sharper and your mind younger. There are 5 different types of puzzles in this book, Consecutive Sudoku, Non-Consecutive Sudoku, Centre-Dot Sudoku (Anti-Diagonal), XV Sudoku, and Greater than Sudoku. The book has 90 puzzles for each type from easy to hard, a total of 450 puzzles with solutions. Consecutive Sudoku is a variation of traditional sudoku with the same rules, i.e. numbers from 1 to 9 to be placed in every row, column, and 3x3 block without repetition. However, consecutive Sudoku takes it little further by consecutive condition, where there are little rectangles between cells that contain consecutive numbers. If there is nothing between the cells, then the numbers on those neighbor cells may have non-consecutive numbers. So, if a cell has number 2 and a little rectangle between it and the next cell, so the next cell should contain 1 or 3. Similarly, if a cell has 9 and the next cell has a consecutive number, logically the number will be 8. But what if the cell has 3, then the next cell that has a consecutive number it will be either 2 or 4, that will be determined according to other rules of sudoku (no repetition). Non-Consecutive Sudoku is a variation of traditional sudoku with the same rules, i.e. numbers from 1 to 9 to be placed in every row, column and 3x3 block without repetition. However, non-consecutive Sudoku takes it little further by non-sequential condition, where there are no consecutive numbers in any adjacent cells either vertically or horizontally. So, if a cell has number 1 then the neighbour cells must not have 2. Most of the time, logic exclusion of the numbers is the main technique to use when solving such puzzles. Centre-Dot Sudoku (Anti-Diagonal) Classic Sudoku has nine 3x3 regions or blocks, but the Centre-Dot Sudoku puzzle has an extra block consists of the centre cells of the other nine regions. The centre dots or cells are shaded and all sudoku rules apply to that tenth region where no repletion in any row or column or block. The Anti-diagonal variation is an added extra step to make solving the puzzles a little easier. Where the diagonal lines should only have at most three different numbers (Repeated numbers are okay in the diagonal line but other sudoku rules as no repetition in the blocks, rows and columns should be followed.) XV Sudoku is an easy but fun sudoku variation where the neighbour cells that add up to 5 have Roman five (v) in between. And the neighbour cells that add up to 10 have Roman ten (X) in between. Greater than Sudoku Greater than Sudoku is a very challenging and twisted Sudoku where the signs > (greater than) and Features