Sandwich Sudoku
Clues give the sum of digits between the 1 and 9 in each row/column
Sandwich Sudoku is fully playable. Choose a difficulty and start solving.
Numbers beside each row and column report the total trapped between that line's 1 and its 9. The whole opening is detective work on where those two crust digits can sit; totals of 0 or 35 give the strongest starts. It feels algebraic — a different muscle from scanning.
For the complete rules, worked examples and solving techniques, read the full How to Play Sandwich Sudoku guide.
Like all Sudoku variants, Sandwich 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 |