A man wants to enter an exclusive club, but doesn’t know the password. He observes a few other patrons:
- First patron walks up and the doorman just says “12”. The patron replies “6” and is let in.
- Second patron walks up and the doorman says “6”. The patron replies “3” and is let in.
Thinking he has figured it out, the man walks up and the doorman says “10”. The man replies “5” but it’s incorrect and he is turned away.
What should the man have said instead?
Solution
3
The man thought the password is to divide the doorman’s number by 2, but in fact the password is the number of letters used to spell the doorman’s number (“twelve” has 6 letters, “six” has 3 letters, and “ten” has 3 letters).
He should have been a bit more patient and observed a few more patrons!