A man wants to enter an exclusive club, but he doesn't know the password. Another man walks to the door and the doorman says 12, the man says 6, and is let in. Another man walks up and the doorman says 6, the man says 3, and is let in. Thinking he had heard enough, he walks up to the door and the doorman says 10, he says 5, and he isn't let in. What should he have said?

Why this works

This riddle plays on the relationship between numbers and the words that represent them. When the doorman says "12," the correct response is not simply half of that number, but rather "6," which is the number of letters in the word "twelve." Similarly, "6" has three letters, hence the response "3." When the doorman says "10," the correct answer is "three," the number of letters in "ten," but the man mistakenly replies with "5," leading to his rejection. The trick lies in recognizing that the password is based on counting the letters, not halving the numbers!