Normal sudoku rules apply. In all cases where the sum of two horizontally or vertically neighbouring digits is A, B or C, a white, grey or black circle is given. A, B and C are different and finding their values is part of the puzzle.
Normal sudoku rules apply. In all cases where the sum of two horizontally or vertically neighbouring digits is A, B or C, a white, grey or black circle is given. A, B and C are different and finding their values is part of the puzzle.