Question 173241
S(n) = the number of tiles required. 
The room is square (and assuming the tiles are square):
n = length of room in tile lengths = width of room in tile lengths
So Area of floor = n x n = n^2
So S(n) = n^2
The miniumum length of the room must be 1 tile length for it to be tileable, so domain: n>=1. Sorry for the edit.

This is my first answer I hope it's right and I hope it makes sense.
All the best.