Medium XV Sudoku
3
7
6
2
6
6
3
9
2
4
6
1
4
9
2
4
7
8
2
5
6
2
1
8
2
3
9
4
7
8
1
8
How to play XV Sudoku
Standard Sudoku rules apply. X between two adjacent cells means they sum to 10. V means they sum to 5. Pairs with no marker are guaranteed not to sum to 10 or 5.
About XV Sudoku
Difficulty
★★★☆☆
3/5
Constraint Type
Cell Relationships
Typical Givens
18–24
Avg. Solve (Medium)
18 min
XV Sudoku (also called Ten-Five Sudoku) places X and V markers between adjacent cells. An X means the two cells sum to 10; a V means they sum to 5. Many XV puzzles use the negative constraint: the absence of a marker guarantees the pair neither sums to 10 nor to 5. Combined with standard Sudoku, this provides very tight constraints across the grid.
Solving Techniques
| Technique | Description | Level |
|---|---|---|
| Negative Constraint | Where no X or V appears between adjacent cells, their sum is neither 10 nor 5. This eliminates (1,9), (2,8), (3,7), (4,6) for X and (1,4), (2,3) for V. | Beginner |
| Sum Pair Enumeration | List all digit pairs that sum to 10 (for X) or 5 (for V), then use row/column placement to identify which pair must occupy each marked pair. | Beginner |
| Marker Chain Logic | Multiple consecutive X and V markers in a row form a sum chain — enumerate valid assignments for the entire chain simultaneously. | Intermediate |
| Box X-Interaction | An X pair forces both digits into specific positions within their shared box, constraining all remaining cells of that box. | Advanced |
Average Solve Time by Difficulty
Easy
8 min
Medium
18 min
Hard
35 min
Expert
62 min