Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GMAT score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Christina scored 760 by having clear (ability) milestones and a trackable plan to achieve the same. Attend this webinar to learn how to build trackable milestones that leverage your strengths to help you get to your target GMAT score.
Re: If a two-digit positive integer has its digits reversed, the resulting
[#permalink]
Show Tags
12 Jan 2014, 15:28
1
Walkabout wrote:
If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(A) 3 (B) 4 (C) 5 (D) 6 (E) 7
The answer has to be a factor of 27, the only option that's a factor of 27 is 3.
Sice \((10x + y) - (10y + x) = 27\), you can simplify this relationship by subtracting with a common factor --> 9x - 9y = 27 ---> 9(x - y) = 27 ---> here, you already notice that the difference has to be a factor of both 9 and 27, but you can simplify further ---> x - y = 3, and thus we have the answer.
But these last steps are superfluous if you already notice that the answer has to be a factor of 27, this way you save time without having to calculate.
Re: If a two-digit positive integer has its digits reversed, the resulting
[#permalink]
Show Tags
18 Feb 2015, 22:12
2
1
Hi All,
Even though this question might seem a little strange, you do NOT need to do any excessive math to get to the correct answer. With just a bit of 'playing around' you can use 'brute force' to get to the answer.
We're told that a 2-digit number has its digits reversed and the difference between those two numbers is 27.
IF we use.... 11 and 11, then the difference is 0 - this is NOT a match
12 and 21, then the difference = 9 - this is NOT a match
13 and 31, then the difference = 18 - this is NOT a match (notice the pattern though? The difference keeps increasing by 9!!!!! I wonder what the next one will be???)
14 and 41, then the difference = 27 = this IS a match
The question asks for the difference in the two DIGITS. The difference between 1 and 4 is 3.
Re: If a two-digit positive integer has its digits reversed, the resulting
[#permalink]
Show Tags
15 Jul 2016, 04:31
3
salr15 wrote:
If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(A) 3 (B) 4 (C) 5 (D) 6 (E) 7
Let’s first label the original two-digit integer as N. We can then say that N = 10A + B, where A is the tens digit and B is the units digit of N.
If this is hard to see let’s try it with a sample number, say 24. We can say the following:
24 = (2 x 10) + 4
24 = 20 + 4
24 = 24
Getting back to the problem, we are given that if the integer N has its digits reversed the resulting integer differs from the original by 27. First let’s express the reversed number in a similar fashion to the way in which we expressed the original integer.
10B + A = reversed integer
Since we know the resulting integer differs from the original by 27 we can say:
10B + A – (10A + B) = 27
10B + A – 10A – B = 27
9B – 9A = 27
B – A = 3
Since B is the tens digit and A is the units digit, we can say that the digits differ by 3.
close
88% (01:18) correct 
