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I have 9 coins that look identical, but one is heavier than the others. I want to identify that one.
My brother has an old-fashioned balance scale that I can use, but I'll have to do annoying chores for him for every time I use that scale (that is, every time I use it to compare the weights of two (sets of) coins). Can you help me find the heavier coin using the scale as little as possible?
• The scale can handle the weight of all coins together, so there is no restriction in that regard.
• Please give not only the number of times you need to weigh, but also explain what you weigh and why.