Easy Diagonal Sudoku
3
9
7
2
7
6
3
7
5
4
8
9
5
8
4
1
7
8
3
4
6
2
7
9
8
1
7
9
8
5
9
6
1
2
3
7
2
4
How to play Diagonal Sudoku
Standard Sudoku rules apply: place 1–9 in every row, column, and 3×3 box. The extra rule: both highlighted diagonals (↘ and ↙) must also contain each digit exactly once. The center cell sits on both diagonals, making it the most constrained cell on the board.
About Diagonal Sudoku
Difficulty
★★☆☆☆
2/5
Constraint Type
Extra Regions
Typical Givens
22–28
Avg. Solve (Medium)
10 min
In Diagonal Sudoku, the standard 9×9 rules apply — but with one powerful extra constraint: both main diagonals (top-left to bottom-right, and top-right to bottom-left) must each contain every digit from 1 to 9 exactly once. This extra constraint typically makes the puzzle easier to solve since diagonals act as two extra units for elimination.
Solving Techniques
| Technique | Description | Level |
|---|---|---|
| Diagonal as a Unit | Treat each diagonal exactly like a row or column — every digit 1–9 appears exactly once. Standard scanning and counting apply. | Beginner |
| Diagonal–Box Interaction | When a digit on a diagonal is confined to one box segment, eliminate it from the rest of that box. | Intermediate |
| Diagonal Naked Pairs | If two cells on a diagonal share the same two candidates, eliminate those values from all other diagonal cells. | Intermediate |
| Three-Unit Intersection | A cell on the main diagonal also belongs to a row, column, and box — four constraint units simultaneously — maximising elimination power. | Advanced |
Average Solve Time by Difficulty
Easy
4 min
Medium
10 min
Hard
20 min
Expert
40 min