How do I know that a certain number has been placed in all the necessary cells? Follow Tap the gear icon in the top right corner. Tap Settings. Enable the Hide Used Numbers option. Numbers that have been placed in all 9 cells correctly will disappear from the bottom panel of the game screen. Related articles How points are calculated? I think some of the sudoku cannot be solved. The numbers can't fit in correctly. How do I know that the sudoku is solved correctly and complete? How do I erase all the numbers and notes that I've entered? How do I use hints? Comments 0 comments Article is closed for comments.