Checking my answer not sure on this one

Ok!! so what you're going to do first is find the area, which in this case is easy 
area of a square= lxw 
= 200 x 200 
=40,000 

So, to find out how much wax you need, divide the area by how much 1/2 a bottle would cover. Or if you want, you could multiply how much 1/2  a bottle would cover by 2 to give you how much one full bottle will cover (which is probably easier) 

so if you go with the second solution, divide the area by how much one bottle will cover so 1 bottle= 2000 x 2 = 4000 

40000 / 4000 = 10 

hopefully that makes sense :)