9×9 · Medium to expert
Sandwich Sudoku
Border clues tell you the sum of the digits sandwiched between the 1 and the 9 in each row and column.
About sandwich
What sandwich sudoku feels like.
Sandwich sudoku adds a clever arithmetic twist made popular by online puzzle channels. Numbers printed outside the grid tell you the sum of all digits that sit between the 1 and the 9 in that row or column — the digits 'sandwiched' between them. Classic sudoku rules still apply; the sandwich clues replace most starting digits.
Rules
- Standard sudoku rules apply: each digit 1–9 appears once per row, column, and 3×3 box.
- A clue outside a row or column gives the sum of the digits between the 1 and the 9 in that line.
- A clue of 0 means the 1 and the 9 are adjacent, with nothing between them.
- The 1 and 9 can appear in either order along the line.
History
Sandwich sudoku was popularised around 2019 through online solving channels and quickly became a staple of variant-sudoku competitions.
- Key rule
- Clues give the sum of digits between the 1 and the 9 in each line
- Difficulty range
- Medium to expert
- Tips
- Start with 0 and small clues — they pin the 1 and 9 close together.
- Large clues like 35 force the 1 and 9 far apart, near the ends of the line.
- List the digit combinations that add to each sum, then place them like a mini puzzle.