As the name suggests, hidden quads are four cells containing only four distinct candidates in a row, column, or region. The last of my Sudoku tips for this article is to look for hidden quads. Remove any instance of these four numbers from the other cells in this row. In the example at the left, the naked quads are circled. Naked quads are like naked triples with the exception that four cells contain only four distinct candidates in a row, column, or region. Sudoku Tips -Naked QuadsĪnother Sudoku tip is to look for “naked quads”. Do you think hidden triples are tough to find? Try quads. Remove the extra numbers from the cells circled in red. If you look at the example at the left, you will see three cells circled in red. Hidden triples like hidden pairs have additional digits that camouflage the three candidates. Hidden triples like naked triples are restricted to three cells in a row, column, or region. See how these Sudoku tips help you solve puzzles? Hidden Triples When you remove the 6,9 from two cells and the 5,6 you will discover a naked pair (1,4) and a hidden single (2). Therefore, you can remove all 5,6, and 9s from the other cells in this row. Only a 5,6 and 9 can appear in those three locations. In the example at the left, the three cells circled are the three naked triples. Quite often only two of the three candidates will be shown. Unlike naked pairs, naked triples do not need all of the three candidates in every cell. Naked triples like the name suggests are three numbers that do not have any other numbers residing in the cells with them. Sudoku Tips -Naked TriplesĪnother Sudoku tip is to look for “naked triples”. Hidden pairs will appear often in your Sudoku puzzles and games. It is safe to remove all other digits from the two cells circled in red so that only the two and nine remain. They are “hidden” because the other numbers in the two cells make their presence harder to spot. Hidden pairs are identified by the fact that a pair of numbers occur in only two cells of a row, column, or region.
In the example at the left there is a hidden pair 2 and 9. The 3,4,6, and 8 quads are really “hidden pairs”. In the naked pair example, it is safe to eliminate the four and six from the two quads of 3,4,6, and 8. When you see a naked pair, it is safe to eliminate those two numbers from all other cells in the row, column, or region the pair reside in. This combination of candidates will occur often also. A naked pair is two identical candidates in a particular row, column, or region. In the example to the left there is a “naked pair”. When there is a lot of candidates showing from the surrounding rows, columns, and regions, a hidden single can be hard to spot. Likewise in the bottom cell the only number that can go there is a four. In this example, the third cell from the top is a seven. The extra candidates in the cell “hide” the single solution. Hidden singles have only one place they can go. In the example at the left there are two hidden singles. Below is another example of a hidden single. No doubt you also noted in this example that once you solved for the naked nine, the 7,9 pair’s solution became a naked single. If you didn’t pencil in all the possible candidates, the naked nine would be less obvious. All the other nines may be crossed off leaving a 6,8 pair, 6,7 pair, a single 7, and a 4,6,8 triple. In the example to the left, you can see the naked single is the nine. If there is one cell that contains a single candidate, then that candidate is the solution for that cell. If there aren’t any other candidates showing, Sudoku players call this a naked single.Įvery naked single allows us to safely eliminate that number from all other cells in the row, column, and region that the naked single lies in. Sudoku Tips -Naked Single CandidatesĮvery Sudoku puzzle will have cells that have only one possible candidate.
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In these cases use my free blank grid with candidates worksheet. The paper version, board games, and handhelds usually lack this capability.
Some online puzzles allow you to pencil in your candidates. Some Sudoku computer programs have the option to show you all the possible candidates.
This leads me to my first of several Sudoku tips and that is pencil in all the possible candidates for each cell, row, column, and region. I prefer to use the process of elimination to solve Sudoku. You can use logic retaining in your memory the possible candidates for each cell, row, column, and region or you can write the candidates down. There are two ways to approach the Sudoku Solving process.
To solve the hardest puzzles and games, use advanced strategies such as X-Wing, XY-Wing, and Swordfish. Apply these Sudoku tips and you will solve most Sudoku puzzles. It may seem impossible to you to solve anything but the most simple Sudoku puzzles. When you begin to play Sudoku, you probably will have moments when you reach a roadblock.
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