XV Sudoku
X between cells means they sum to 10; V means they sum to 5
XV Sudoku is fully playable. Choose a difficulty and start solving.
An X between two cells means they total 10; a V means they total 5; a blank edge guarantees neither. That silent negative rule does as much work as the printed letters. Easy to pick up, surprisingly deep once you mine the unmarked edges.
For the complete rules, worked examples and solving techniques, read the full How to Play XV Sudoku guide.
Like all Sudoku variants, XV Sudoku builds on the classic 9×9 foundation. Every row, column, and 3×3 box must contain each digit from 1 to 9 exactly once. The variant constraint is added on top of these standard rules, never replacing them.
If you're new to Sudoku, start by learning the basic rules and techniques before attempting variants.
Techniques Useful for This Variant
| Technique | How it applies |
|---|---|
| Pencil Marks / Notes | Essential for tracking candidates alongside the variant constraint |
| Obvious Singles | Cells narrowed to one candidate by the combined constraints |
| Hidden Singles | Digits with only one valid cell in a unit after variant elimination |
| Pairs and Triples | Locked candidates exposed by the additional constraint |