Answer
280 is not perfect because:
1 + 2 + 4 + 5 + 7 + 8 + 10 + 14 + 20 + 28 + 35 + 40 + 56 + 70 + 140 ≠ 280
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Answer
280 is not perfect because:
1 + 2 + 4 + 5 + 7 + 8 + 10 + 14 + 20 + 28 + 35 + 40 + 56 + 70 + 140 ≠ 280