4 times are enough for4 2 ,but you need 5 times.

來源: Jinjing 於 2010-05-02 14:03:37 [] [舊帖] [給我悄悄話] 閱讀數 : (109 bytes)
回答: 用天平稱39個乒乓球 由 Blue_Diamond 於 2010-05-01 21:01:19

Welcome you back,your formula are quite good,but can improve.If 3 for 13 were wrong,I would be totally wrong.

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