回複：5th grader math rocks! problem - r u smarter than a 5th grade

來源: Jinjing 於 2010-02-09 17:08:48 [] [舊帖] [給我悄悄話] 閱讀數 : (198 bytes)

S=3*13(1+3^3+3^6+3^9+.....+3^57)
=3*5*2*2*2(1+3^4+3^8+3^12+....+3^56)
=3*11*11(1+3^5+3^10+......+3^55)
So,S is divisible by 2x2x2x3x5x11x11x13.
Ha,I can graduate from elementary school.

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• brilliant -一用戶- ♂ 給 一用戶 發送悄悄話 (0 bytes) () 02/09/2010 postreply 19:00:04

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