Button Summary
Press this button to switch the number keypad to the opposite side of the game. (Lefties may prefer it on the left.)
The digit assistant is activated by this button. It will partially solve your puzzle using the easiest techniques, leaving the more difficult moves to you.
When the digit assistant is active, you may turn on auto answer.
You may turn the sound effects on or off with this button.
This button controls visibility of the timer.
Undo and Redo access your complete move history.  
The eraser removes the answer or your notes, whichever is visible, in the selected (highlighted) cell.
This button will cause any wrong answers to turn red. You may then use undo to return to the point where you made your first error.
Use this button to change the pencil color for your answers.
This is the reset button. Your options are to reset the entire puzzle, reset the notes or reset the digit assistant.
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