My calculation for 189

来源: 润润 于 2005-03-11 18:11:18 [] [旧帖] [给我悄悄话] 阅读数 : (357 bytes)

Since ABC/(A+B+C) = 1 + (99A + 9B)/(A+B+C) which
is a decreasing function of C, C should be 9.
Again when C = 9, ABC/(A+B+C) = 1 + 9[1 + (10A - 9)/
(A+B+9)] which is also a decreasing function of B.
Hence B = 8.
Finally, when C = 9, B = 8, ABC/(A+B+C) = 100 - 1611/(A+17) which is an increasing function of A, So A = 1.

ABC = 189.

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