Normal sudoku rules apply, and all instances of two neighbouring cells that sum to 10 or 5 are marked with X (10) or V (5). The grid is a torus, so "neighbouring cells" include those at opposite ends of rows/columns.
Normal sudoku rules apply, and all instances of two neighbouring cells that sum to 10 or 5 are marked with X (10) or V (5). The grid is a torus, so "neighbouring cells" include those at opposite ends of rows/columns.