Created
May 9, 2011 14:19
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Short python script to show that if you could fold a piece of paper in half 50 times, its thickness will be 3/4 the distance from the Earth to the Sun (71 million miles). Discovered on a very interesting Quora question.
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""" | |
Folding paper in half 50 times is 3/4 of the distance from earth to sun | |
From: | |
http://www.quora.com/What-are-some-of-the-most-mind-blowing-facts#answer_526501 | |
Thickness of a sheet of paper: 0.1 mm (~0.004 inches) | |
""" | |
def fold(num_folds=50, thickness=0.1): | |
"""Simulate folding a sheet of paper in half. | |
``num_folds`` is the number of times we'll fold the paper in half. | |
``thickness`` is the the thickness of a sheet of paper (in millimeters). | |
""" | |
for i in range(1, num_folds + 1): | |
thickness = thickness * 2 | |
if thickness >= 10000: | |
# convert to kilometers | |
t = thickness / 10000.0 | |
units = 'km' | |
elif thickness >= 1000: | |
# convert to meters | |
t = thickness / 1000.0 | |
units = 'm' | |
elif thickness >= 100: | |
# convert to centimeters | |
t = thickness / 100.0 | |
units = 'cm' | |
else: | |
# keep in millimeters | |
t = thickness | |
units = 'mm' | |
fmt_string = '{n} folds, thickness = {thickness:G} {units}' | |
print(fmt_string.format(n=i, thickness=t, units=units)) | |
if __name__ == "__main__": | |
n = input("\n\nHow many folds? ") | |
fold(n) |
@BjarkeCK I just noticed your comment. Yes, you're correct, but the default number of significant digits (the ndigits
parameter) causes a rounding error, there. A more precise example might be:
>>> fold(5, ndigits=3)
1 folds, thickness = 0.008 inches
2 folds, thickness = 0.016 inches
3 folds, thickness = 0.032 inches
4 folds, thickness = 0.064 inches
5 folds, thickness = 0.128 inches
Better yet, we should use millimeters, centimeters, kilometers instead an antiquated system of measurements ;)
Updates:
- Switched to metric units.
- Removed the
ndigits
parameter; using the:G
formatting option to round/format output - Can now be run interactively; e.g. with
python paper.py
Please correct your code. It must be:
if thickness >= 1000000:
# convert to kilometers
t = thickness / 1000000.0
units = 'km'
elif thickness >= 1000:
# convert to meters
t = thickness / 1000.0
units = 'm'
elif thickness >= 10:
# convert to centimeters
t = thickness / 10.0
units = 'cm'
else:
# keep in millimeters
t = thickness
units = 'mm'
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1 fold = 0.01
2 fold = 0.02
Then 3 fold = 0.04 and not 0.03 right?