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KGS math club/solution 11 27

Revision as of 09:43, 27 November 2014 by YogSothoth (talk | contribs) (Created page with "Split the coins into two piles: 64 and 32 coins. Flip every coin in the pile of 64. Now both piles have equal number of heads. Proof: let n be the number of heads in the origina...")
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Split the coins into two piles: 64 and 32 coins. Flip every coin in the pile of 64. Now both piles have equal number of heads.

Proof: let n be the number of heads in the original pile of 32 (so n is between 0 and 32). Now the original pile of 64 has 64-n heads. When every coin is flipped, the pile of 64 has 64-(64-n)=n heads as well.

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