Source: Official Guide for GMAT Review 2016 Problem Solving; #216

1

If a two-digit positive integer has its

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?

2 Explanations

1

PRANAVA SHEORAN

Let the number be ab, where a is the digit at 10s place and b is the digit at ones place. The number formed by reversing the digits of ab is ba. Note that ab = 10a+b and ba = 10b+a. So (ab - ba) = [(10a+b)-(10b+a)] = [9(a-b)]. Since the difference of 2 numbers is 27 , 9(a-b) = 27. Therefore, (a-b) =3

Nov 4, 2016 • Comment

Sam Kinsman, Magoosh Tutor

That's right Pranava! Good job solving this one, and thanks for sharing your answer! :D

Nov 4, 2016 • Reply

1

Gravatar Mike McGarry, Magoosh Tutor

Aug 17, 2015 • Comment

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Official GMAT Material

Official Guide for GMAT Review 2016

Official Guide for the GMAT 2015 14th Ed.

Official Guide for the GMAT 13th Ed.

Official Guide for the GMAT 12th Ed.

Revised GRE PDF 2nd Ed.


Section 5.3 Problem Solving

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