OK, here's mine...
Easy one first...
(1) An Archaeologist was digging the ground. One of his student found what looks like a very old coin. "Professor, this looks like a great discovery!", said the student. The professor took the coin and saw the coin was dated "3049 B.C." He said quietly "This coin must be a fake." What was his logic for the conclusion?
Now a more difficult one...
(2) The time is ancient China... The emperor just chopped the head off of his prime minister. He needed the poor guy's replacement. He wanted the brightest person in his empire. The "search committee" eventually narrowed down the candidates to only three persons. Because all three were so smart that no exam was able to tell who was the smartest.
The committee therefore decided to open an ancient secret scroll which was supposed to decribe an "ultimate" test of intelligence. Here we go...
Three candidates were led into a small room, facing to each other. They were told the following.
Examiner: "We have TWO green ribons and THREE blue ribons. Now, close your eyes. I'm going to stick one of these ribons on your forehead."
Candidates all closed their eyes, while the Examiner was putting a ribon on each one's forehead.
Examiner: "Open your eyes. Now tell me the color of your ribon. If you are the first one who gets the correct answer, you will be the next prime minister with full pension benefits. If you get it wrong, your head will be chopped off immediately, so don't gamble. Be very logical."
Each candidate can see the colors of the other two candidates, but not his own.
For a while, no one said a thing. Finally, one person stood up and said "Mine must be blue" which was correct. What was his logic?