And second, you could guess equations without 1, 2, or 8 to narrow down the missing digit in only two more guesses.
Edit: Brain fart on the first part, but I think the second part would have helped within three more guesses.
And second, you could guess equations without 1, 2, or 8 to narrow down the missing digit in only two more guesses.
Edit: Brain fart on the first part, but I think the second part would have helped within three more guesses.