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If N is a positive three-digit number that is greater than 200, and each digit of N is a factor of N itself, what is the value of N?
(1) The tens digit of N is 5.
(2) The units digit of N is 5.
==>Since we have 3 digit integer in the original condition, we have 3 variables and we need 3 equations to match the number of variables and equations. Since we have 1 each in 1) and 2), E is likely the answer.
Using 1) & 2), n=555 and is a unique answer. Therefore C may seem like the answer. However, since this is an integer problem, considering common mistake type 4(A) (If it's easily C, consider A, B), we can look at this again. 1) gives us n =555 as a unique answer, but 2) gives us n= 555, 515 which is not unique, and therefore not sufficient.
Therefore A, not C, is the answer.
These problems are 495,051 level problems that are related to variable approach method and common mistake types,
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