That must be equal to 1cm^2, right? I guess you could cheat and use the area of a thumb nail, but then you could take it a step further and use the area of a h

That must be equal to 1cm^2, right? I guess you could cheat and use the area of a thumb nail, but then you could take it a step further and use the area of a horse's fingernail, which is at least 100 times larger...