To add a cell value

• Drag & drop value from bottom buttons or from other cells using mouse.
• Select the cell and enter value using keyboard.

To remove a cell value

• Drag & Drop the same value again from bottom buttons or from other cells using mouse.
• Re-enter the value to get toggled, using keyboard.

To clear all values in a cell

• Drag & Drop the cell into itself
• Drag & Drop the cell into a game fixed cell
• Press delete using keyboard.

To enable pencil mark

• Enter multiple values to cell to get pencil mark.
• For single value cell, double click to toggle pencil mark.

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