which formula works best

good morning Tech gurus

a question please about which formula will work for the following (my excel knowledge nor my matchs is good enough).

I have 4 different bedroom sized flats 1 beds 2 beds 3 bed and 4 beds

they are split over 26 floors of a tower block.

for example I have 4 one beds on the 26th floor, and 2 on each of another 15 floors

 I am trying to find a way to show someone who uses a drop down that if they choose from a drop down say one beds and then choose the 15th floor it returns the quantity 2

or  another way to look at it is, I have x57 three bed flats and there are 4 of these on floor levels 10/11/12/13/14

theres one on the ground floor

and then x2 on a further 20 floor levels

how can I represent this in excel please

many thanks

Philip