There are 12 coins, 1 of which is false, you do not know if the false coin weighs more or less than the other 11, you have a balance scale which balances one side with the other. You have 3 weighs to guarantee finding which is the coin. I have asked the smartest people I know and so far no one has solved it. If you do have an answer please start a conversation with me and I will tell you if its correct or not. So as not to spoil it for anyone viewing this. Just post, "I have sent you my solution" or something.