Nine

Sudoku techniques explained

Eight techniques, eight boards

Stuck on a sudoku? Then one of these eight techniques is almost always the next move. They are in the order you learn them: from what you see at a glance to what you have to hunt for. Each one comes with a real board where it is the next step, and the reasoning underneath.

1. Naked single · Only option in Nine
2. Hidden single · Only place in Nine
3. Pointing pair
4. Box line reduction · Box claimed in Nine
5. Naked pair
6. Hidden pair
7. Naked triple
8. X-wing

In the app

Nine is the sudoku that writes this reasoning itself, on every puzzle, in the app. The explanation fills in nothing: it names the technique, colours the proof and says why. Free for seven days, then a one-time unlock. No ads, no account, no internet needed.

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