The question as it appears in the 06/12 edition of Specs & Techs from GlobalSpec:
You have ten boxes, numbered 1 to 10, each with 100 identicallooking coins; the coins in one box are counterfeit. The only measurable difference is that the box of bad coins weighs 5 grams less than the others. Using a very accurate scale, determine which box contains the bad coins. You are limited to one weighing on the scale!
Thanks to en who submitted the original question.
(Update: June 19, 8:44 AM EST) And the Answer is...
Take out one coin from box #1, then two coins from box #2, three coins from box #3, etc. Weigh all boxes together on the scale. If the reading differs from the calculated weight by 5 grams, then box #1 is counterfeit; if the difference is 10 grams, then the second box is counterfeit, etc.

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