Sudoku variant · rules and tips
Kropki Dots
A white dot between two cells means their digits are consecutive, differing by one. A black dot means one digit is exactly double the other. Small dots, large opinions.
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The Professor's tips
How do you solve Kropki Dots?
01 / Warm up
Start on a 4 by 4 grid
- With digits 1 to 4, a white dot admits 1 and 2, 2 and 3, or 3 and 4. A black dot admits 1 and 2, or 2 and 4.
- Notice that 3 can never sit beside a black dot here. Doubling it gives 6, halving it gives one and a half, and neither is on offer.
- Follow the dots in chains. If A joins B by a white dot and B joins C by a black one, the constraints compound, and the chain often solves itself.
02 / Level up
Then try a 6 by 6 grid
- With digits 1 to 6, a black dot admits only 1 and 2, 2 and 4, or 3 and 6. Three pairs in total, which is very restrictive indeed.
- A white dot admits five pairs, from 1 and 2 up to 5 and 6. Once either digit is known, the other has at most two options left.
- A cell touching both a white dot and a black one is pinned tightly. Apply both conditions together and very little survives.
- In these lessons the dots are positive clues only. The absence of a dot tells you nothing, though you may meet a stricter form elsewhere in which silence is also evidence.
The rule, drawn
What does Kropki Dots look like?
Start with a single square
Where can you play Kropki Dots?
Kropki Dots is one of the 17 variants in Cryptic, each with a lesson and unlimited puzzles.
Get it onGoogle PlayPlay on the web