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About Killer Sudoku Puzzles

Killer Sudoku Puzzle Rules

The rules of Killer Sudoku are as follows:

Here is an example start position of a killer sudoku:

Killer Sudoku Puzzle

If you are familiar with standard sudoku, you will see the one key difference: the introduction of addition into the grid. Whereas in standard sudoku the numbers 1-9 have no numerical meaning, and could be replaced with letters, here they do have significance as numbers too. Look at the top-left of the grid: there is a red cage (dashed-line region) of three squares, that must sum to 11. This means that the values in those three squares could for instance be 2,3,6 as that sums to 11. But they could not be 2,3,7 as that sums to 12 so would not obey the sum total, nor could they contain 3,5,3 as whilst that sums to 11 it repeats a digit and that is against the rules.

If you would like a visual explanation of the rules, here is a video outlining the killer sudoku rules as explained above:

Play A Sample Killer Sudoku Puzzle

If you'd like to have a go at solving the example puzzle above, then you can do so for free online with our Online Killer 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 Kakuro Puzzle puzzle every day of the year, together with many other fun and interesting logic puzzles.

Strategy and Solving Tips for Killer Sudoku

Killer sudoku puzzles are trickier than standard sudoku. It is not uncommon to spend quite a lot of time to begin with working out possible values for squares, rather than necessarily placing numbers straight away as may be the case with a standard sudoku. However they can all be solved without any guesswork, just logic is required to reach the unique solution. Here are some solving tips:

If you'd like to see a visual explanation of the rule of 45, then here is a video that goes through what we've just outlined above: