Put three coins on one side of the balance scale and three on the other. If one side tips up, the fake is amongst them. If they balance, the fake is one of the three unweighed coins. Weigh two of the three coins known to contain the fake, one on each side of the scale. If the scale rises, the fake is on the high side. If they balance, the unweighed coin is the fake. :-D
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)