The positive two-digit integers x and y have the same digits, but in reverse order. Which of the following must be a factor of x + y?
A) 6
B) 9
C) 10
D) 11
E) 14
OA: D
The positive two-digit integers x and y
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The question asks is to find what MUST be true.boomgoesthegmat wrote:The positive two-digit integers x and y have the same digits, but in reverse order. Which of the following must be a factor of x + y?
A) 6
B) 9
C) 10
D) 11
E) 14
OA: D
So, a quick and simple solution is to TEST some values. If a statement turns out to be FALSE, we can eliminate that answer choice.
Let x = 12 and let y = 21
So, x + y = 12 + 21 = 33
Now check the answer choices.
A) 6 is not a factor of 33. ELIMINATE A
B) 9 is not a factor of 33. ELIMINATE B
C) 10 is not a factor of 33. ELIMINATE C
D) 11 IS a factor of 33. KEEP D
E) 14 is not a factor of 33. ELIMINATE E
Answer: D
Cheers,
Brent
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Hi boomgoesthegmat,
This question is perfect for TESTing VALUES (as Brent's approach shows). One of the great aspects about this question is that there are a variety of options that you can use to find the correct answer.
Brent ended up using 12 and 21, for a total of 33
But you could also use...
25 and 52, for a total of 77
13 and 31, for a total of 44
23 and 32, for a total of 55
Etc.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
This question is perfect for TESTing VALUES (as Brent's approach shows). One of the great aspects about this question is that there are a variety of options that you can use to find the correct answer.
Brent ended up using 12 and 21, for a total of 33
But you could also use...
25 and 52, for a total of 77
13 and 31, for a total of 44
23 and 32, for a total of 55
Etc.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich