BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

If the two-digit integers \(M\) and \(N\) are positive and have the same digits, but in reverse order, which of the foll

Expert replies
by Gmat_mission » Sat Oct 31, 2020 6:43 am

Timer

00:00

Answers

A

B

C

D

E

Stats

Difficulty

If the two-digit integers \(M\) and \(N\) are positive and have the same digits, but in reverse order, which of the following cannot be the sum of \(M\) and \(N?\)

A) 181
B) 165
C) 121
D) 99
E) 44

Answer: A

Source: Official Guide
Join the discussion
Source: — Problem Solving |

If the two-digit integers M and N are positive and have the same digits, but in reverse order, which of the following cannot be the sum of M and N

Let the unit's digit of M be m
So, its tens digit becomes m
Therefre, M can be written as M = 10m + m = 11m
Similarly, let the unit's digit of N be n
So, its tens digit becomes n
Therefre, N can be written as N = 10n + n = 11n

Now, M + N = 11m + 11n = 11 (m+n)

Therefore, all the options should be a multiple of 11.
Only 181 is not a multiple of 11 among the given options. Therefore, answer is option A.
Join the discussion