rules
Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns, 3x3 box.rules
Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns, 3x3 box. The white dots indicate all the adjacent/neighbouring cells in which the difference between the two cells is 1. The black dots indicate all the adjacent cells in which one digit is the double of the other one. The dot between two cells with digits 1 and 2 has any of these two dots.