ESL Discussion

A man used to work in 11th storey building. His office is situated in 11th floor of the building. Everyday he woke up at 6 O' clock and get ready for office. Later always go for Bus Stop. Exactly 7'O clock he board for bus number 420 and it destined to near his office. Next he entered the Lift and by this he go to 9th floor of office building. Rest 2 floor he uses the stair and then entered his office exactly 8'O Clock. Exactly 5'O clock his working time ends and he go inside the lift and directly moves to ground floor. At 5:10 PM he uses same bus number 420 and reaches his home.

It is his daily routine of Home to Office and Office to Home. He was forced to climbed 2 floor by using stairs.

The million dollar question is why he can not go directly to 11th floor instead of going to 9th floor?

PS: It's a brainy and logical reasoning question.