hard

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?
Common Wrong Answers
“Five”
The man guessed five based on halving the number given by the doorman, but the riddle requires counting the number of letters in the word for the number.
“Ten”
Saying ten is incorrect because it does not follow the pattern of the previous interactions, which is not about the numerical value but rather the number of letters in the words.
“Six”
Guessing six is incorrect as it assumes a simple division of the number given instead of recognizing that the answer should be based on the word 'ten', which has three letters.