Normal sudoku rules apply, and any instance of neighbouring cells summing to 5, 10 or 15 is marked with V (5), X (10) or XV (15) between the cells. If there is no mark between them, two neighbouring cells do not add to 5, 10 or 15.
Normal sudoku rules apply, and any instance of neighbouring cells summing to 5, 10 or 15 is marked with V (5), X (10) or XV (15) between the cells. If there is no mark between them, two neighbouring cells do not add to 5, 10 or 15.