Looking on the internet deeply has found these results:

on the 2nd floor is the most popular phrase on the web.

in the 2nd floor 17,610,000 results on the web	on the 2nd floor 114,300,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Mother told me that in our house on the 2nd floor, in apartment number 3 3 spotted on the 2nd floor. He'll want the south wing of the 2nd floor. it is here where we now stand The back room on the 2nd floor. We believe there is a children onto the 2nd floor. before the war, Dr. Lem had lived with his son Stanislav. Kwon Sam Su, head of National Security, currently lives in central Pyeongyang, Gyeongsangdong district, in the Cheollim Apartments, 2nd floor, unit 3.	chan, please wait on the 2nd floor. It was as I had lived since birth in the street Brayerovskoy, 4, on the 2nd floor. it is here where we now stand Shu Mother told me that in our house on the 2nd floor, in apartment number 3 before the war, Dr. Lem had lived with his son Stanislav. The janitor said you were on the 2nd floor balcony at about 11 o'clock. I said I'll be on the 2nd floor.

in the 2nd floor

17,610,000 results on the web

on the 2nd floor

114,300,000 results on the web

More popular!

Mother told me that in our house on the 2nd floor, in apartment number 3
3 spotted on the 2nd floor.
He'll want the south wing of the 2nd floor.
it is here where we now stand
The back room on the 2nd floor.
We believe there is a children onto the 2nd floor.
before the war, Dr. Lem had lived with his son Stanislav.
Kwon Sam Su, head of National Security, currently lives in central Pyeongyang, Gyeongsangdong district, in the Cheollim Apartments, 2nd floor, unit 3.

chan, please wait on the 2nd floor.
It was as I had lived since birth in the street Brayerovskoy, 4, on the 2nd floor.
it is here where we now stand
Shu
Mother told me that in our house on the 2nd floor, in apartment number 3
before the war, Dr. Lem had lived with his son Stanislav.
The janitor said you were on the 2nd floor balcony at about 11 o'clock.
I said I'll be on the 2nd floor.