Sudoku Classic Free

Sudoku, originally called Number Place,is a logic-based, combinatorial 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-grids that compose the grid (also called "boxes", "blocks", "regions", or "sub-squares") contains all of the digits from 1 to 9. The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a unique solution.

Rules
Fill in the grid so that every row, column, and 3x3 box contains digits 1 through 9.

Digit Entry Modes
* Tap on the screen to change cell selection
* Tap on numeric keys to enter values, or eraser to clear current cell.
* Click pen button to ON/OFF Pencil Marks mode.

Pencil Marks:
To switch between entering pencil marks and actual values select the pencil icon on the input button.
* Horizontal Pencil: pencil marks mode is OFF.
* Upright Pencil: pencil marks mode is ON.
* When mode marks is ON, using numeric keys to enter pencil marks. Click eraser button to clear marks in the current cell.

About Helper Hints:
The helper uses logic to find the next logical move. The cell values it reveals is not for an arbitrary cell, but rather the next logically solvable one.
Can't disable this mode.