You have a basket of 9 oranges, 8 of the oranges have the same weight and 1 is heavier than the others. All the oranges looks and feels the same. You have a scale but you are allowed to use it only 2 times. How could you find the heaviest orange?
Split the nine oranges into
Three piles of three, piles A, B, and C.
Compare the weights of
Piles A and B. If they weigh the same, the heavy orange is in pile C. If either of those two piles are heavier, the heavy orange is in that pile.
Then, compare the weights of
Two of the oranges from the heavier pile. If they're the same, then the third orange is the heaviest. If either of those two are heavier, then that's the heaviest orange.
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