If you scan each column that has an 8 as depicted by the two red arrows, you will find three cells where it is possible that an 8 could be placed. In the example at the right, we have two 8s. You will use this technique to help you solve every Sudoku puzzle from easy to fiendish. I touched upon the Sudoku strategy called scanning in my article “How To Play Sudoku”. Usually, however, you will need to add a few more strategies. Some easy Sudoku puzzles may be solved using only this one technique. You will be able to use this simple Sudoku strategy in every Sudoku puzzle, if not at first, then eventually. Well, sure enough! The cell circled in red (R5C5) has to be a “6” since there isn’t any other choice. Well a “9” can not go there because cell R4C6 of the same region has a “9” in it.

Well an “8” can not go there because cell R5C7 of the same row has an “8” in it. Well a “7” can not go there because cell R9C5 of the same column has a “7” in it. Well a “6” might go there since there isn’t any “6” in the same row, column, or region. Well a “5” can not go there because cell R2C5 of the same column has a “5” in it. Well a “4” can not go there because cell R5C4 of the same region has a “4” in it. Well a “3” can not go there because cell R5C9 of the same row has a “3” in it. Well a “2” can not go there because cell R1C5 of the same column has a “2” in it. Well a “1” can not go there because cell R5C1 of the same row has a “1” in it.

To solve the cell circled in red, say to yourself, “What number can or can not go here?”. After all, every row, column, and region has several empty cells. Can you find the only choice that will satisfy the cell circled in red?Īt first glance you might think that there aren’t enough cells filled in to solve it. Any child can solve for the missing cell when they know the Sudoku rules.Īt the left we have a third example of a cell that can be solved using the one and only choice Sudoku strategy. That is the answer, so fill the cell in with an “8”.Ībove we have another example where all the cells are filled in a region, except for the cell circled in red. In the example above, the cell circled in red can be solved quickly by looking for the missing number. In my article “How To Play Sudoku”, I touched upon the Sudoku strategy to look for a cell in every row, column, and region that can be solved by looking for the only possible choice.

Sudoku x wing rules