Bunuel wrote:
a, b, and c are positive integers. If a, b, and c are assembled into the six-digit number abcabc, which one of the following must be a factor of abcabc?
(A) 16
(B) 13
(C) 5
(D) 3
(E) none of the above
Let's think of abc as a number (NOT a product).
So, for example, if a = 1, b = 2 and c = 5, then abc = 125, and abcabc = 125125
In this regards, abcabc = abc000 + abc
= abc(1000 + 1)
= abc(1001)
= abc(7)(11)(13)
So, abcabc must be divisible by 7, 11 and 13
Answer: B
Cheers,
Brent
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