The rules of Sudoku Puzzles are compellingly simple:
Place 1-9 once in each region of the grid. The regions are the rows, the columns, and the 3x3 bold-outlined boxes
Here is an image of the start position of a sudoku puzzle:
The chances are that you are already familiar with sudoku, since in the last 15 years or so, it has come to be a popular puzzle in virtually every newspaper and magazine around the world. This certainly didn't use to be the case - the crossword used to rule supreme, and most other puzzles seen were also word puzzles. Number and logic puzzles tended to only be seen occasionally or in variety publications, but the simple logic puzzle sudoku changed all that.
Play A Sample Sudoku Puzzle
If you'd like to have a go at solving the example puzzle shown above, you can do so for free online with our Online Sudoku 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 Puzzle puzzle every day of the year, together with many other fun and interesting logic puzzles.
Strategy and Solving Tips for Sudoku Puzzles
The most common way to solve a sudoku puzzle is to scan each row, column and box and see if there is only square in each of the 27 regions where a particular number can go. For instance, in the sample grid above, look at the bottom-right 3x3 box and ask yourself where the 9 can go in that region. It should be fairly obvious there is only one place where it can go - the middle square in the box, and so you should place it there.
Most people use pencilmarks to a greater or lesser extent to solve sudoku puzzles. Depending on how hard the puzzle is and your experience level, these may be minimal or more extensive. One method that is popular for puzzles that are medium or easy difficulty is to restrict pencilmarking to boxes, and only using them when there are 2 candidates for a value in a box. For instance, in the example grid above, we would pencilmark the 1s in the middle box of the grid into the two squares that can contain them. This method strikes a good balance between using minimal pencilmarks whilst recording sufficient information to often help you solve a puzzle. Of course if a puzzle proves trickier, then you may need to move to more extensive pencilmarking. The key is to remember which type of pencilmarks you are using so you don't get confused mid-solve!
There are lots of complicated strategies out there, and websites dedicated to covering these. However, to solve the vast majority of puzzles in mainstream puzzles such as newspapers, you will never need anything more difficult than X-wings, and to solve many puzzles up to medium level in mainstream publications you'll just need to cover the basics and be sure not to miss anything obvious.
This video explains the X-wing strategy and how it can be used to help make progress when solving fiendish sudoku puzzles:
