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Written by CodeGuru


I guess the answer has something to do with sphere packing problem.

So, the area of the coin is pi*R^2=0.785
Area of the box is 2000.

The ideal case of full filling ex. square coins: 2546 coins (never happends, but gives an upper limit).

According to Wikipedia good packaging have an average density of ~0.90, so 2000 x 0.90=1800 sq inches.

1800 / 0.785 = 2292.xxx

So, the answer should be 2292

http://en.wikipedia.org/wiki/Sphere_packing


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Written by Job-Interview


Good thinking, but this puzzle is not Fermi problem and I don't think you can solve it by approximations. There is an exact answer which is way off from yours :)


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Written by Student-looking-for-job

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Written by Job-Interview


Nope. BTW, no tricks, pure math.


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Written by AmCook


Yeah, cool puzzle.

Thought not a good one for the interview as it requires a lot of calculations. My answer is 2011, it is based on the idea of using space beteen round coins.

See below:

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