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由題意可得:所有的三位數有9A92=648個,然後根據題意將10個數位分成三組:即被3除餘1的有1,4,7;被3除餘2的有2,5,8;被3整除的有3,6,9,0,若要求所得的三位數被3整除,則可以分類討論:每組自己全排列,每組…
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