If you could fold a piece of paper fifty times the height of the stack would be approximately the distance from Earth to the sun. And if you folded it one more time, the height would be the distance from Earth to the sun and back. It's what's known in mathematics as a geometric progression.
I quoted the question from the fascinating book "The Tipping Point" by Malcolm Gladwell. He uses this as an illustration of a point he makes int he book. The book, by the way, is not about math but about what creates the tipping points that cause things, be it a product's success, an epidemic, etc. to occur.