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Welcome to the Sudoku-X 16 x 16 Puzzle Books Series. The puzzles in the “Hard” version are ideal for those wanting to move on from the “Medium” difficulty level and try a more challenging set of puzzles that require some advanced solving techniques.

Even though this book is described as “Hard”, some experienced solvers may find it too easy to complete. There is nothing more frustrating than purchasing a puzzle book only to find that it is either not challenging enough or too difficult to complete. Please read the full description to determine if the difficulty level of this book matches your level of solving skills.

The Sudoku-X 16 x 16 Puzzle Book series is available in the following difficulty levels: Easy, Medium, Hard, Very Hard and Extreme. All difficulty levels are available in the following formats: Sudoku and Sudoku-X

In my classic 16 x 16 Sudoku-x puzzles, the grid is 16 cells wide and 16 cells deep. The lines of squares running horizontally are called rows, and the lines running vertically are called columns. The grid is further divided by thicker lines into sixteen 4 x 4 square boxes.

Sudoku-x follows the same rules as a standard Sudoku puzzle with one exception, and that is the two diagonal lines of shaded cells that run from corner to corner.

The aim of the puzzle is to fill the blank cells with the correct numbers and letters. Each row, column, 4 x 4 box and shaded diagonal must end up containing all of the numbers from 1 to 9 and all the letters from “a” to “g”. Each number and letter can only appear once in any row, column, 4 x 4 box and shaded diagonal.

**How the Puzzles are graded:**

Difficulty levels are determined by the complexity of the methods used to deduce the correct solution: Each level (Hard, Very Hard & Extreme) necessitates a mode of deduction which was not required in the previous level. The “Easy” and “Medium” Difficulty levels require no advance solving techniques, however, in the “Easy” level, there will always be one or more cells that can be filled-in, whereas, in the Medium level there is sometimes only one cell that can be filled-in at any one time.

Easy: Ideal for beginners or those that simply want a very easy to solve Sudoku-X puzzle. No Advanced solving techniques required.

Medium: A little more challenging than the “Easy” difficulty level. You may have to check a lot of rows, columns and 4 x 4 boxes before finding a cell that can be filled in. As with the “Easy” difficulty puzzles, advanced solving techniques are not required.

Hard: The “Hard” difficulty level puzzles do require some advanced solving methods to be employed. These puzzles are more suited to those learning to use more complex deduction processes and moderately experienced Sudoku-X puzzle solvers.

Very Hard:The “Very Hard” series is one step up from the “Hard” level, forcing the solver to use more complex deduction methods. This level is definitely one for the more experienced solvers and the Sudoku-X fanatic.

Extreme: As the difficulty level suggests, these puzzles are extremely difficult to complete. Unless you are an expert Sudoku-X solver, these puzzles may be too hard for you.

- 100 Hard Sudoku-X 16 x 16 Puzzles
- Large 8.5 x 8.5 inch Book Layout
- Easy to read (1 Puzzle per Page)
- Some Advanced Solving Techniques Required
- Bonus Puzzles
- Solutions Included

#### Product details

**Series:**Sudoku-x Puzzle Books 16 x 16 – 100 Hard Puzzles (Book 1 of 5)

**Paperback:**130 pages

**Publisher:**Independently published (July 17, 2019)

**Language:**English

**ISBN-10:**1081149876

**ISBN-13:**978-1081149871

**Product Dimensions: **5 x 0.3 x 8.5 inches

**Shipping Weight:**4 ounces