While studying about covering problems in combinatorics, I got to a simple question:
What polygons can be covered exactly, without any area that is covered twice or area that is outside the covered area?
For example, all parallelogram that is $n^2$ times magnified can be exactly covered by original parallelogram, as following.
Are there any research known about this property, such that the polygon can be exactly covered by original polygon when magnified $n^2$ times?