## PUZZLE |

**Sudoku X Puzzle Rules**

The rules of Sudoku X Puzzles are as follows:

- Place the numbers 1-9 once in each row, column and 3x3 box of the grid. This is the standard sudoku rule set.
- In addition, there are two shaded diagonal regions in the grid, which together form the shape of the letter 'X'. These regions must also contain 1-9 once only. This is the additional rule of sudoku X.

Here is an image of the start position of a sudoku X puzzle:

Sudoku X is one of the more commonly seen variants of sudoku, and one of the easiest to understand, as there are no new rules as such, just additional regions. Whereas standard sudoku on a 9x9 grid has 27 regions, in a sudoku X puzzle there are 29 regions instead. The key to solving them is to remember that these two extra regions exist and using the information they provide to help you reduce the options for squares and hence solve the puzzle.

**Play A Sample Sudoku X Puzzle**

Like to have a go at the sudoku X puzzle that is displayed above? Then you can do so for free online with our Online Sudoku X Puzzle Player

If you enjoy this puzzle type, you can join our online Puzzle Connoisseur's Club for £12 or $17 a year and play a new Sudoku X Puzzle puzzle every day of the year, together with many other fun and interesting logic puzzles.

**Strategy and Solving Tips for Sudoku X Puzzles**

All of our sudoku X puzzles have a single solution that can be reached through the use of logical rules alone, no guessing is ever required. In order to solve a sudoku X puzzle you will use the same logic as with standard sudoku, but remembering to apply it to the diagional 'X' regions, too; here are some solving tips:

- Practice scanning the diagonal regularly rather than just the rows, columns and boxes to help you make progress. This is the key difference to remember between sudoku X and regular sudoku. For instance, look at the top-left to bottom-right diagonal of the sample puzzle. Where can the 3 go in this region? Now look at the other diagional: where can the 8 go in that region? In both cases you should be able to restrict it to three locations instantly.
- Remember to use pencilmarks, or 'small numbers' on our player tool, to keep track of what can go where. Using a keyboard, press the space bar to toggle between big and small numbers.
- The central square in the puzzle is the most powerful as it is in five different regions: row five, column five, the middle box, and both the diagonal regions. Therefore once this square is placed, be sure to bear in mind how much of the rest of the grid it sees. Look at the image below, where the 4 has been placed in the centre of the grid. This information can be used to instantly place the 4 in the top-left box, which it turn enables us to instantly place the 4 in the top-right box; can you see how?