If you are one of those people who has gone crazy over the Japanese logic game, Sudoku, the chances are you are ready for some Sudoku tips. This puzzle comes in all different levels of difficulty so if you have leveled off at a certain skill level, some Sudoku tips may help you to keep moving upward in puzzle difficulty.

Sudoku is a puzzle of numbers which is published daily in newspapers and magazines around the world. Although the first puzzle appeared in the 1970s in Dell Magazines, a publisher of all kinds of puzzle and activities books, it didn’t become extremely popular until after it was introduced in Japan in the paper, the *Monthly Nikolist.* Kaji Maki, president of the company, Nikoli, which publishes the paper, named the puzzle “Suji wa dokushin ni kagiru.” Roughly translated, the Japanese means “the numbers must occur only once.” Thankfully it was shortened to Sudoku.

**How to Play Sudoku** 247

The Sudoku puzzle is a grid that is 9 x 9, which has three sub grids which are 3 x 3. Some of the nine spaces (cells) already have numbers, which are known as “givens.” The whole point of Sudoku is to fill the empty cells with numbers so that every single row, column, and 3 x 3 region contains the numbers 1 – 9. That means that every direction, the numbers 1-9 occur only once, making the name of the puzzle quite appropriate.

While the task of filling the cells with the numbers 1-9 might seem easy, it actually involves some more complicated reasoning to accomplish the task. It also takes a tremendous amount of concentration, especially as you pursue puzzles of greater and greater difficulty.

**Sudoku 247 Tips**

While there are probably as many theories about how to fill in the cells in a Sudoku puzzle as there are people completing them, there are also some general Sudoku tips on how to go about it. While there are entire books published on Sudoku tips and techniques, we will just try to show you some of the basic ways people approach the puzzles and what to do in certain instances when you may be stumped and not know what to do next.

The first thing you need to do when you look at a Sudoku puzzle is to figure out what the possible numbers might be for all of the blank spaces. As you go through the possibilities for each of the cells, you can do it in your head (if you have a very good memory), or you can write down all of the possible numbers (some people use blank Sudoku sheets to do this). Most people use some method of jotting down the numbers as they work through the puzzle. Others use computer programs designed to do exactly this, though a lot of Sudoku players think using your computer to help solve a puzzle is cheating.

One of the first Sudoku tips to try is to locate the naked singles, as they are called. These are cells which have only one possible number. Once you have identified one of these numbers, you know for sure that this number cannot be used again in that particular row, column, or 3 x 3 block. The best way is to start is to look at a row and lightly mark in pencil all of the possible numbers for a cell. This is based on the “givens” in the other rows, columns and 3 x 3 blocks. Because every number 1 – 9 can only be used once, when you write down the possible numbers for each cell, you will have one which comes up with only one possible candidate.

When you are looking for the naked singles, you will most likely uncover some hidden singles, which is the second of our Sudoku tips. Hidden singles occur very frequently. They have only one place or cell where they can go. But, they are hidden until you pencil in all of the possibilities for a certain cell. For instance, you could have a pair of the numbers 4, 5 after you have uncovered the naked singles, 5 is the only possibility left for that cell. Because it was paired with the 4, it was hidden for a time, hence the name, hidden singles.

Sudoku tips are always logical, just like the puzzle. The next logical progression in the elimination of numbers from particular cells is to find the naked doubles and the hidden doubles. The method is exactly the same as it was for naked and hidden singles. A naked pair will have two identical candidates for the 1 – 9 in any particular row, column, or 3 x 3 region.

Hidden pairs, like hidden singles, are hard to spot because of the number of possibilities you have penciled in a particular cell in your Sudoku puzzle. These occur when two numbers remain after you have removed all of the naked and hidden singles and naked doubles. Hidden pairs are very common in these puzzles and very hard to spot.

With this same logic you can next pursue finding naked triples and quads and hidden triples and quads. Quads are quite rare but the theory is that once you find a naked triple, for instance, and eliminate it from consideration, the viable numbers left in the cell might constitute a naked single or a naked double or other combination we already covered in the Sudoku tips above.

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