Normal sudoku rules apply. In each grey caged pentomino, any domino of digits must form a prime number reading left-to-right or downwards. In the central 3x3 box, however, NO domino of digits must form such a prime number.
Normal sudoku rules apply. In each grey caged pentomino, any domino of digits must form a prime number reading left-to-right or downwards. In the central 3x3 box, however, NO domino of digits must form such a prime number.