ryara

Here’s a riddle i found somewhere:

There’s a club. Anyone can join the club.
If they can answer the doormans question.
A man who wants to join stands near the door and listens to the doorman.
A member walks up to the doorman and the doorman says,
“Twelve.”
The member replies, “Six.”
The doorman lets him in.
Another member walks up to the doorman. The doorman says,
“Six.”
The member replies, “Three.”
Feeling confident, the man wanting to join walks up to the doorman.
The doorman says, “Ten.”
The non-member replies, “Five.”
The doorman tells him to leave.
Why?

I haven’t figured out the answer myself yet - but I hope I eventually do. Meanwhile, you may comment if you have a hint of some sort or think you’ve got the answer .