Normal sudoku rules apply. Digits may not repeat on a beige hitline. A circled digit on a hitline indicates how many digits match their position number along that line, starting at the end with the square (which is 'position 1'.) Eg: If a line reads 97325, then the 2 would be circled because there are two digits in their correct positions: 3 is in the 3rd position, and 5 is in the 5th position.