Enter the fifteen roundest and most rectangular countries.
Roundness/rectangularity is determined by the percentage overlap of a country's actual territory with a rectangle or circle of the same area optimally superimposed over it.
Interestingly, the same features that make a country "round" also lend to the country being "rectangular", hence the large amount of overlap between the two categories. This method of evaluating convergence with a shape for any shape prefers countries with regular, straight borders, a high area to perimeter ratio and no major irregularities such as Alaska, Sicily or the various parts of Malaysia. The few that are rectangular but not round are really remarkably rectangular, like Egypts two perfectly-straight borders which are at almost a 90% angle, and Turkey, which fits very well into a rectangular box.