Kropki Sudoku: Rules & How to Solve
Tiny dots between cells encode consecutive and double relationships. Small marks, big chains of logic.
The rule
A white dot between two cells means the digits are consecutive (differ by 1). A black dot means one digit is double the other. Note that not every qualifying pair is necessarily marked, so check each puzzle's rules.
How to solve kropki sudoku
Black dots love small digits
A black dot pair must be one of {1,2}, {2,4}, {3,6}, or {4,8} — only four options, which prunes candidates quickly.
Chains of white dots
A run of white dots forms a consecutive sequence, behaving much like a short renban or thermo without the direction.
Use the absence carefully
When the puzzle states all dots are given, a missing dot tells you two neighbours are neither consecutive nor in a 1:2 ratio.
Frequently asked questions
- What does a white dot mean in Kropki sudoku?
- The two cells it sits between hold consecutive digits, such as 4 and 5.
- What does a black dot mean?
- One cell is exactly double the other — {1,2}, {2,4}, {3,6}, or {4,8}.
- Are all Kropki dots always given?
- Not necessarily. Many puzzles, including VariantDoku's, note when dots may be omitted, so don't assume a missing dot rules a relationship out unless stated.
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