Very nice little game, it's kind of meditative and makes you focus on the method.
The YES/NO buttons after each round feel like they don't really match the style of the rest of the game graphics wise, and perhaps it would benefit from some music, I'm not sure.
I ran into trouble when there were repeating numbers. I can't think of any way to finish a level with 2 identical numbers without guessing. It would be good if each level could be finished every time given the correct strategy.