Well, assuming the square painting has a side length of 62 cm on ONE side only (meaning the other 3 sides will be the same) then we can use the normal area equation for squares. Area=S^2, where s is the side length of 1 side.
So, put in your info: Area=62^2.
62^2=62*62 basically. That equals 3844
Assuming that 62 cm is the length of only 1 side of the square, your answer is 3844 cm^2.