Sudoku is a logic-based number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 sub-boxes contains all digits from 1 to 9.
Select a cell on the board and tap a number to fill it in. Use Notes mode to pencil in candidate numbers. Each number can only appear once in each row, column, and 3×3 box.
Start with the easiest cells — look for rows, columns, or boxes that are almost complete. Use the Notes feature to track possible candidates and eliminate them as you progress.