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/ /___/ /_/ / /_/ /  __/ /  / /___/ /_/ / /_/ /
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Sphere Packing

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What is the length of the shortest pipe, of internal radius 50mm, that can fully contain 21 balls of radii 30mm, 31mm, ..., 50mm?

Give your answer in micrometres (10^(-6) m) rounded to the nearest integer.

https://projecteuler.net/problem=222