self Maths Puzzle

A man while looking at a photograph said, "Brothers and sisters have I none. That man's father is my father's son."

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self Other Question

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. Another member came to the door and the doorman said, "six." The member replied, "three"and was also let in. The man thought he had heard enough and walked up and knocked on thedoor. The doorman said, "ten" and the man replied, "five." He was not let in. What should he have replied and why? This guy living on the 20th floor in an apartment building got up early each morning to go to work in a downtown store. He always went into the elevator on the 20th floor and rode down to the entrance (1st floor). When he came home he always rode the elevator from the entrance and up to the 8th floor. He walked out of the elevator and walked the stairs up to his apartment on the 20th floor.

Why didn't he take the elevator all the way up to his apartment?