Neighbours
      
In a square in which the houses are evenly spaced around the outside, numbers 
3 and 10 are opposite each other.

What is the smallest number of houses in the square?

This is the smallest amount of houses that could be in the square because if 
there were any less to make the 3 and the 10 be opposite each other makes it a rectangle.  

What is the largest possible number of houses in the square?
   
The largest possible amount of houses in the square is the same as the smallest because any
bigger and it would be a rectangle.  

There are infinite rectangular possibilities.