Thats a nice apartment building you have there! How did you decide where to put it?
I decided to put my apartment building on the 30th floor because it has a great view of the city and I am at an even distance from the other places in my apartment.
I put my apartment on the 30th floor because it would be an easier way for me to get to a certain location in my apartment such as the pool or the restaurant. The restaurant is 30 floors above me so it is +30. The gym is 16 floors above my apartment so it would be +16. Also the movie theater is 11 floors below me so it would be -11. The pool is 28 floors below me so it is -28. Lastly, the lobby is 30 floors below me so it would be at -30.
Since my apartment is on the 30th floor, I need to go down 30 floors to the lobby. If my apartment would be considered 0 on the number line than it would be 0 + -30= -30. Which means that the lobby is 30 floors under me.