GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 17 Oct 2019, 21:09

### GMAT Club Daily Prep

#### 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

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

# Consider the binary operation # defined by a#b = 10a + b, where the op

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58404
Consider the binary operation # defined by a#b = 10a + b, where the op  [#permalink]

### Show Tags

21 Mar 2018, 23:11
00:00

Difficulty:

15% (low)

Question Stats:

76% (01:04) correct 24% (01:07) wrong based on 48 sessions

### HideShow timer Statistics

Consider the binary operation # defined by a#b = 10a + b, where the operations on the right side of the equal sign denote the standard arithmetic operations. Suppose M = x#y and N = y#x, where x and y are positive integers, which of the following must be a factor of M + N ?

(A) 14
(B) 11
(C) 10
(D) 9
(E) 6

_________________
Intern
Joined: 14 Mar 2018
Posts: 10
Re: Consider the binary operation # defined by a#b = 10a + b, where the op  [#permalink]

### Show Tags

21 Mar 2018, 23:18
Bunuel wrote:
Consider the binary operation # defined by a#b = 10a + b, where the operations on the right side of the equal sign denote the standard arithmetic operations. Suppose M = x#y and N = y=x, where x and y are positive integers, which of the following must be a factor of M + N ?

(A) 14
(B) 11
(C) 10
(D) 9
(E) 6

I believe N = y#x here

Then M+N becomes 11a+11b
B
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3074
Re: Consider the binary operation # defined by a#b = 10a + b, where the op  [#permalink]

### Show Tags

Updated on: 22 Mar 2018, 02:07

Originally posted by EgmatQuantExpert on 22 Mar 2018, 01:06.
Last edited by EgmatQuantExpert on 22 Mar 2018, 02:07, edited 3 times in total.
examPAL Representative
Joined: 07 Dec 2017
Posts: 1140
Re: Consider the binary operation # defined by a#b = 10a + b, where the op  [#permalink]

### Show Tags

22 Mar 2018, 01:08
Bunuel wrote:
Consider the binary operation # defined by a#b = 10a + b, where the operations on the right side of the equal sign denote the standard arithmetic operations. Suppose M = x#y and N = y=x, where x and y are positive integers, which of the following must be a factor of M + N ?

(A) 14
(B) 11
(C) 10
(D) 9
(E) 6

As there are only variables in the equation, we'll pick easy numbers.
This is an Alternative approach.

Say x = y = 1. Then x#y = 10+1 = 11 and y#x = 1+10 = 11
Then M+N=22. Only (B) , 11, is a factor of 22.

(B) is our answer.
_________________
Re: Consider the binary operation # defined by a#b = 10a + b, where the op   [#permalink] 22 Mar 2018, 01:08
Display posts from previous: Sort by

# Consider the binary operation # defined by a#b = 10a + b, where the op

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne