Dear Dr. Rob

Why can't paper be folded in half more than seven times? Is this even true?

Shane, 10, Vic

Dr Rob:

This is a great one to try yourself.

If you choose a regular piece of paper, you will struggle to fold it in half more than seven times. Every time you fold paper in half, it gets twice as thick and half as big. After a few folds, it will get too small and too thick to fold.

But the problem is not impossible. In fact, a high school student proved this in 2001. She worked out that all you needed was big enough and thin enough paper. She aimed for 12 folds, so she calculated she needed (very thin) toilet paper that was 1.2 km long.

After the 12^th fold it was roughly 30cm long, and stacked up over half a metre.

But it was possible.