Imagine you would have to put a rope around the moon. Since the moon is 1,738,000 metres in diameter, this is a hard task.
Finally you have managed to get the rope around the moon but... it is one meter short.
You decide to dig a groove all around the moon, so that the shorter rope suffices. How deep must this groove be?
(Assume the Moon to be a perfect sphere.)
(In reply to re: answer
by Dej Mar)
Thanks for pointing out the typing error. I actually meant centimeters instead of meters.
Made the necessary corrections to my earlier post.