The Exponential Folding

How many times do you need to fold a piece of paper (A4 size) in half, to make it reach the moon? Assume that the paper is 0.1 mm thick and that the distance to the moon is 384,403 kilometers (238,857 miles) — the accepted average.

When you calculate this, you should find that there are only 42 folds necessary. Welcome to the world of exponentials!