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 and the nine outlined 3x3 regions.A cross between two cells indicates that the product of the numbers in these cells is less than 10. A plus between two cells indicates that the sum of the numbers in these cells is less than 10. If the sum and product are less than 10, then there is a cross between these cells. If there is no sign between two cells, then both sum and product are at least 10.
In order to get the best gaming experience on smart devices such as smartphones or ipads, the touch screen mode is preferred. On your PC, you can choose keyboard mode or touch screen mode according to your preference.