A man wanted to enter an exclusive club but did not know the password that was required. He waited by the door and listened.

A club member knocked on the door and the doorman said, “Twelve.� The member replied, “six� and was let in.

A second member came to the door and the doorman said, “Six.� The member replied, “Three� and was let in.

The man thought he had heard enough and walked up to the door. The doorman said,�Ten� and the man replied, “five.� But he was not let in.

What should have he said?