Category Archives: Solving tips

Instructions on how to solve Sudoku and other puzzles. Detailed solving tips and techniques for various kinds of puzzles, including Sudoku variants.


A while ago I explained the X-Wing solving technique. Recently I shown my explanation of other basic, Classic Sudoku solving techniques. The only remaining solving method that I don’t consider trial and error is Swordfish. So, to complete the list of Sudoku solving tips, here is an example of a Sudoku puzzle that can be […]
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Classic Sudoku Solving Techniques

It’s about time I finally explained the basic (and most common) Sudoku solving techniques. Most of you are already familiar with these, but for those who aren’t – I’d like to show my explanation. These techniques are used in ALL sudoku puzzles – Classic, Killer, Samurai and others. Make sure you fully understand them before […]
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All puzzles have ONE solution only!

Alright, before you claim that some puzzle has more than one solution, do this: 1. For Samurai puzzles, read this article 2. For other puzzles, make sure the puzzle is not an “X” (diagonal) 3. For puzzles from The Washington Post and The Express, read this post (and also read the article from point 1). […]
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Samurai Sudoku rules

I’ve been asked a few times to post some Samurai sudoku solving tips. Well – there aren’t any special tips that apply exclusively to Samurai. Standard Sudoku rules apply, but to make things clear for newcomers, I’d like to give a brief set of instructions. Rules of Samurai Sudoku 1. Each Samurai Sudoku puzzle consists […]
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Twin Nonets

Lets formalize the technique that can be used when solving overlapping puzzles, which I have been referring to as “the new solving technique” and that I now call Twin Nonets. Basically, this technique is a sub-technique (or if you like – a consequence) of the naked/hidden triplets technique that you are all probably aware of. […]
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UPDATE: I changed the image to reflect an actual X-Wing. As a matter of fact, this is the puzzle that I posted a couple of days ago under the “daily Sudoku” page. Here is a quick explanation for the “X-Wing” technique. Suppose you reach the following position and you can’t go any further: Tweet You […]
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As promised, I implemented the Swordfish classic Sudoku solving technique in my Perfect Sudoku software and generated a few puzzles. I just posted one of them on the Daily Sudoku page. However, I ran my generator and generated a couple of thousands Killer Sudokus and NONE of them required Swordfish, just as I speculated before. […]
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