I have a bag containing the digits 0 through 9, and used six of them to stick two different three-digit perfect squares on the foreheads of Paul and George. Both Paul and George know this fact, but each one can see only the other's number.
I ask Paul, "How many of the digits remaining in my bag can you exactly tell me?"
Paul replies, "Three."
If I now ask the same question to George, what should he reply?
(In reply to
re: George's answer by Charlie)
Actually he does. The 1 or a 7 will be on Paul's forehead and he can see that. The one that is not on Paul's forehead will be in the bag.
re(2): George's answer
