Q. How many seconds are there in 20 minutes?

Sudoku Puzzle #139 - Nightmare

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Sudoku Puzzle Books

If you prefer to play with pencil and paper, we have several books of quality sudoku puzzles published - if you like them we'd love you to leave a review on Amazon! They also make an excellent gift for the enthusiastic sudoku solver!

Sudoku Puzzles

300 Sudoku Puzzles: Easy to Extreme

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Sudoku Puzzles

150 Sudoku Puzzles: Easy - Vol. 1

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Sudoku Puzzles

150 Sudoku Puzzles: Medium - Vol. 1

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Sudoku Puzzles

150 Sudoku Puzzles: Hard - Vol. 1

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Our sudoku rating system

The easy sudoku puzzles will require nothing more complicated than simple singles and the occasional direct pointing method. These are easy to do just by scanning the grid and looking for lines to isolate a cell where a particular number can only go (hidden singles) or looking for cells where there is only one possibility left (naked singles and full houses).

Our mild to medium sudoku puzzles up the difficulty a notch by adding in moderate techniques like naked and hidden pairs, and pointing and claiming. These introduce you to the idea of elimination of possible options (or candidates) leaving you with the simple singles you find in the easy level. You may want to start thinking about writing candidates into the cells at this stage to help you spot and keep track of the candidates you eliminate. This is about as hard as you'll find in most magazines and newspapers, even at their "expert" or "very hard" level.

Moving onto our hard sudoku puzzles level, we introduce some more advanced techniques for eliminating candidates such as triplets, wings (including the infamous X-Wing!) and a few of the easier fish, single digit patterns, unique rectangle methods and colouring. You will need to write down candidates to spot these!

But we aren't going to stop there. For the real enthusiasts we have a fiendish and diabolical sudoku levels with the more complicated fish (some with fins!) and wings, loops, chains and almost locked sets.

And for the masters of sudoku, our extreme and nightmare sudoku level will require the use of forcing chains, nets and the Kraken Fish! Hellishly difficult, but yet solvable using pure logic.

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