Techniques · sudoku
Cell Forcing Chains
Try each candidate of one cell in turn. Every choice leads to the same result, so that result must be true.
In the walkthroughs, every Cell Forcing Chains step shades the cells of the pattern and names the cell and digit it proves, so you can see the move on the grid rather than read about it. Press “Skip to next hard step” to jump straight to it.
Worked examples
Puzzles from the books where Cell Forcing Chains is used. Each link opens the full step-by-step solution.
Extreme Sudoku 1 (101 of 150 puzzles)
- Puzzle 20 · Expert 5
- Puzzle 21 · Expert 5
- Puzzle 23 · Expert 5
- Puzzle 30 · Expert 5
- Puzzle 31 · Expert 5
- Puzzle 35 · Expert 6
- Puzzle 37 · Expert 6
- Puzzle 40 · Expert 7
Extreme Sudoku 2 (118 of 150 puzzles)
- Puzzle 18 · Expert 5
- Puzzle 21 · Expert 5
- Puzzle 24 · Expert 6
- Puzzle 25 · Expert 6
- Puzzle 26 · Expert 6
- Puzzle 27 · Expert 7
- Puzzle 28 · Expert 6
- Puzzle 29 · Expert 7
Extreme Sudoku 3 (118 of 150 puzzles)
- Puzzle 17 · Expert 5
- Puzzle 23 · Expert 6
- Puzzle 24 · Expert 6
- Puzzle 25 · Expert 6
- Puzzle 26 · Expert 7
- Puzzle 27 · Expert 7
- Puzzle 29 · Expert 7
- Puzzle 30 · Expert 7
Where it sits
See the whole ladder on hard sudoku techniques, or look a puzzle up by number under solutions.
