Techniques · sudoku and killer sudoku
Coloring/Multi-coloring
Following one digit’s strong links, cells get two colours: one colour is true and the other is false. A cell that sees both colours cannot hold the digit.
In the walkthroughs, every Coloring/Multi-coloring 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 Coloring/Multi-coloring is used, those where it is the key technique first. Each link opens the full step-by-step solution.
Extreme Sudoku 1 (9 of 150 puzzles)
- Puzzle 9 · Expert 5
- Puzzle 51 · Expert 7
- Puzzle 53 · Expert 7
- Puzzle 54 · Expert 5
- Puzzle 96 · Expert 7
- Puzzle 97 · Expert 7
- Puzzle 98 · Expert 7
- Puzzle 103 · Expert 8
Extreme Killer Sudoku 1 (96 of 150 puzzles)
- Puzzle 2 · Expert 2 · key technique
- Puzzle 6 · Expert 4 · key technique
- Puzzle 7 · Expert 3 · key technique
- Puzzle 8 · Expert 3 · key technique
- Puzzle 12 · Expert 3 · key technique
- Puzzle 14 · Expert 3 · key technique
- Puzzle 15 · Expert 3 · key technique
- Puzzle 17 · Expert 3 · key technique
Extreme Sudoku 2 (15 of 150 puzzles)
- Puzzle 13 · Expert 7
- Puzzle 27 · Expert 7
- Puzzle 36 · Expert 7
- Puzzle 41 · Expert 7
- Puzzle 43 · Expert 7
- Puzzle 46 · Expert 5
- Puzzle 80 · Expert 7
- Puzzle 81 · Expert 7
Extreme Killer Sudoku 2 (90 of 150 puzzles)
- Puzzle 1 · Expert 2 · key technique
- Puzzle 3 · Expert 2 · key technique
- Puzzle 5 · Expert 3 · key technique
- Puzzle 8 · Expert 3 · key technique
- Puzzle 12 · Expert 2 · key technique
- Puzzle 16 · Expert 2 · key technique
- Puzzle 22 · Expert 2 · key technique
- Puzzle 24 · Expert 3 · key technique
Extreme Sudoku 3 (13 of 150 puzzles)
- Puzzle 23 · Expert 6
- Puzzle 27 · Expert 7
- Puzzle 41 · Expert 5
- Puzzle 53 · Expert 6
- Puzzle 70 · Expert 7
- Puzzle 71 · Expert 7
- Puzzle 82 · Expert 7
- Puzzle 118 · Expert 7
Extreme Killer Sudoku 3 (93 of 150 puzzles)
- Puzzle 4 · Expert 2 · key technique
- Puzzle 6 · Expert 2 · key technique
- Puzzle 8 · Expert 4 · key technique
- Puzzle 16 · Expert 4 · key technique
- Puzzle 21 · Expert 4 · key technique
- Puzzle 22 · Expert 3 · key technique
- Puzzle 26 · Expert 3 · key technique
- Puzzle 27 · Expert 3 · key technique
Where it sits
See the whole ladder on hard sudoku techniques and hard killer sudoku techniques, or look a puzzle up by number under solutions.
