Medium Kropki Sudoku
Ready to sharpen your skills? Medium Kropki Sudoku puzzles introduce interactions between the variant constraint and classic Sudoku techniques. You'll need to combine both skill sets to progress.
What to expect at Medium level
Medium Kropki Sudoku puzzles require you to combine the variant constraint with standard Sudoku deduction - Naked pairs, hidden singles, and unit scans. The constraint is more tightly woven into the grid, so you'll need to think a few steps ahead.
Best suited for players comfortable with Easy Kropki Sudoku who want to build their pattern recognition.
Difficulty overview
About Kropki Sudoku
Kropki Sudoku places dots between pairs of adjacent cells. A white dot means the two digits differ by exactly 1 (consecutive). A black dot means one digit is exactly double the other (e.g., 2 and 4, or 3 and 6). Where no dot appears, neither condition applies. Some Kropki puzzles use the 'negative constraint' where the absence of a dot guarantees neither condition holds, giving even more information.
Solving Techniques for Medium Level
| Technique | Description | Level |
|---|---|---|
| White Dot Pairs | White dots mark consecutive digit pairs: (1,2), (2,3), …, (8,9). Cross-reference with row and column constraints. | Beginner |
| Black Dot Pairs | Black dots mark double-relationship pairs: (1,2), (2,4), (3,6), (4,8). Only these four combinations are valid. | Beginner |
| Negative Constraint | No dot between two cells means they are neither consecutive nor in a 1:2 ratio — a powerful elimination on every unmarked adjacent pair. | Intermediate |
| 1-2-4 and 2-4-8 Chains | A black dot adjacent to a white dot often forces the common 1→2→4 or 2→4→8 chain. | Intermediate |
Master these, then take on Hard Killer Sudoku to learn Advanced techniques.