Britney Gallivan Britney Gallivan Britney Crystal Gallivan (born 1985) of Pomona, California, is best known for determining the maximum number of times that paper or other materials can be folded in half. In January 2002, while a junior in high school, 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 maximum number of times any piece of paper could be folded in half was seven. She calculated that, instead of folding in half every other direction, the least volume of
ISO 216 follow the same ratio principle as the A series pages. For example, if an A4 page is folded in half so that it is A5 in size, it will fit into a C5 envelope (which will be the same size as a C4 envelope folded in half). The lengths of ISO C series paper are therefore ≈ 1.09 times those of A-series paper. A, B, and C paper fit together as part of a geometric progression, with ratio of successive side lengths of , though there is no size half-way between B"n" and A("n" − 1): A4, C4, B4, "D4",