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[[Image:Britney Gallivan Folding.jpg|280px|thumb|right|Britney Gallivan having made the 11th fold]] | |||
'''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. | |||
==Biography== | |||
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 eleven 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 paper to get 11 folds would be to fold in the same direction, using a very long sheet of paper. A special kind of $85-per-roll toilet paper in a set of six met her length requirement. Not only did she provide the empirical proof, but she also derived an equation that yielded the width of paper or length of paper necessary to fold a piece of paper of thickness ''t'' any ''n'' number of times. | |||
She was a keynote speaker at the September 22, 2006 [[National Council of Teachers of Mathematics]] convention. | |||
In 2007, Gallivan graduated from [[University of California, Berkeley]] with a degree in Environmental Science from the College of Natural Resources. | |||
==Paper folding theorem== | |||
{{Further2|[[Mathematics of paper folding]]}} | |||
An upper bound and a close approximation of the actual paper width needed for alternate-direction folding is | |||
:<math> | |||
W = \pi t 2^{(3/2)\left(n-1\right)}. | |||
</math> | |||
For single-direction folding (using a long strip of paper), the exact required strip length ''L'' is | |||
:<math> | |||
L = \frac{\pi t}{6}\left(2^{n}+4\right)\left(2^{n}-1\right), | |||
</math> | |||
where ''t'' represents the thickness of the material to be folded, ''W'' is the width of a square piece of paper, ''L'' is the length of a paper piece to be folded in only one direction and ''n'' represents the number of folds desired. | |||
These equations show that, in order to fold anything in half, it must be <math>\pi</math> times longer than its thickness, and that, depending on how something is folded, the amount its length decreases with each fold differs. | |||
==In popular culture== | |||
Gallivan's story was mentioned in the episode ''[[List of Numb3rs episodes|Identity Crisis]]''<ref>[http://pomonahistorical.org/12times.htm Folding Paper in Half 12 Times]</ref> of ''[[Numb3rs]]'', She served as a consultant and was mentioned in an episode of ''[[MythBusters]]''<ref>[http://kwc.org/mythbusters/2007/04/episode_72_underwater_car_and.html Annotated Mythbusters]</ref> on the [[Discovery Channel]] in 2007, and in episode 3 of ''[[QI]]'''s "F" series. | |||
==See also== | |||
* [[Mathematics of paper folding]] | |||
* [[Origami]] | |||
* [[Recreational mathematics]] | |||
==References== | |||
<references/> | |||
==Further reading== | |||
* Clifford A. Pickover, ''The Math Book'' (Stirling, New York, 2009) p. 504 | |||
==External links== | |||
* [http://pomonahistorical.org/12times.htm Historical Society of Pomona Valley Page] | |||
* [http://mathworld.wolfram.com/Folding.html Folding at MathWorld] | |||
* {{SloanesRef |sequencenumber=A076024|name=Loss function for folding paper in half}} | |||
{{Persondata <!-- Metadata: see [[Wikipedia:Persondata]]. --> | |||
| NAME = Gallivan, Britney | |||
| ALTERNATIVE NAMES = | |||
| SHORT DESCRIPTION = American high school student who discovered the maximum number of times different types of paper could be folded | |||
| DATE OF BIRTH = 1985 | |||
| PLACE OF BIRTH = | |||
| DATE OF DEATH = | |||
| PLACE OF DEATH = | |||
}} | |||
{{DEFAULTSORT:Gallivan, Britney}} | |||
[[Category:1985 births]] | |||
[[Category:Living people]] | |||
[[Category:Paper folding]] | |||
[[Category:University of California, Berkeley alumni]] | |||
[[Category:People from Pomona, California]] | |||
Revision as of 22:36, 23 October 2013
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.
Biography
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 eleven 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 paper to get 11 folds would be to fold in the same direction, using a very long sheet of paper. A special kind of $85-per-roll toilet paper in a set of six met her length requirement. Not only did she provide the empirical proof, but she also derived an equation that yielded the width of paper or length of paper necessary to fold a piece of paper of thickness t any n number of times.
She was a keynote speaker at the September 22, 2006 National Council of Teachers of Mathematics convention.
In 2007, Gallivan graduated from University of California, Berkeley with a degree in Environmental Science from the College of Natural Resources.
Paper folding theorem
An upper bound and a close approximation of the actual paper width needed for alternate-direction folding is
For single-direction folding (using a long strip of paper), the exact required strip length L is
where t represents the thickness of the material to be folded, W is the width of a square piece of paper, L is the length of a paper piece to be folded in only one direction and n represents the number of folds desired.
These equations show that, in order to fold anything in half, it must be times longer than its thickness, and that, depending on how something is folded, the amount its length decreases with each fold differs.
In popular culture
Gallivan's story was mentioned in the episode Identity Crisis[1] of Numb3rs, She served as a consultant and was mentioned in an episode of MythBusters[2] on the Discovery Channel in 2007, and in episode 3 of QI's "F" series.
See also
References
Further reading
- Clifford A. Pickover, The Math Book (Stirling, New York, 2009) p. 504