IQ Level Test

A man wanted to enter a club. Every member of club knows the password. A man did himself beside wall and tried to listen password. A member came, watchman said "twelve" member replied "6" watchman opened the door. Another member came, watchman said "six' member replied "3" watchman open the door. Man thought he had got the password. He went at door watchman said "eight" man replied "4" watchman  did not opened the door. What was the password?