"In January 2002, while a junior in high school, Britney Gallivan demonstrated that a single piece of toilet paper, 4000 ft (1200 m) in length, can be folded in half twelve times. This was contrary to the popular conception that the number of times any piece of paper could only be folded in half was limited to eight times. She folded a very long sheet of toilet paper in half 12 times, posing at the 11th fold to take pictures. She knew that instead of folding in half every other direction the best way to get 12 folds would be to fold in the same direction, using a very long sheet of paper. A special kind of $85 toilet paper met her length and width requirement. Not only did she provide the empirical proof, but she also derived an equation that yielded the width of paper, W, needed in order to fold a piece of paper of thickness t any n number of times."