Sandwich Sudoku, or "Between 1 and 9 Sudoku", is a variant of Sudoku. A YouTube channel introduced this variation.
- Standard Sudoku rules. Place numbers from 1 to 9 in every row, column, and 3×3 box.
- Additionally, outside the grid, there will be some numbers. The numbers indicate the sum of the numbers physically between 1 and 9 in the respective row or column. (that is, if the row is 953126847, the sum of the numbers between 1 and 9 is 8)