f, b, and c are positive integers. If f, b, and c are assembled into the six-digit number fbcfbc, which one of the following must be a factor of fbcfbc?	Choose the correct answer: A) 16 B) 13 C) 5 D) 3 E) none of the above
Plug in some values and check -   fbcfbc = 123123   Not divisible by 16 and 5   let fbcfbc = 125125   Not divisible by 3   Only option (B) and (E) is left in both the cases...   Check once more to marke (13) as correct answer   let fbcfbc = 135135   Again divisible by 13   So, mark answer as (13) 13
<result>B</result>
f, b, and c are positive integers. If f, b, and c are assembled into the six-digit number fbcfbc, which one of the following must be a factor of fbcfbc?