Last visit was: 20 Jul 2025, 11:03 It is currently 20 Jul 2025, 11:03
Close
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
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 20 Jul 2025
Posts: 102,633
Own Kudos:
743,032
 [3]
Given Kudos: 98,235
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,633
Kudos: 743,032
 [3]
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
FacelessMan
Joined: 19 Dec 2015
Last visit: 17 Jul 2020
Posts: 87
Own Kudos:
435
 [6]
Given Kudos: 13
Location: United States
GMAT 1: 720 Q50 V38
GPA: 3.8
WE:Information Technology (Computer Software)
GMAT 1: 720 Q50 V38
Posts: 87
Kudos: 435
 [6]
4
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
General Discussion
User avatar
Divyadisha
User avatar
Current Student
Joined: 18 Oct 2014
Last visit: 01 Jun 2018
Posts: 667
Own Kudos:
Given Kudos: 69
Location: United States
GMAT 1: 660 Q49 V31
GPA: 3.98
GMAT 1: 660 Q49 V31
Posts: 667
Kudos: 1,894
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
OptimusPrepJanielle
Joined: 06 Nov 2014
Last visit: 08 Sep 2017
Posts: 1,779
Own Kudos:
Given Kudos: 23
Expert
Expert reply
Posts: 1,779
Kudos: 1,449
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
If the least common multiple of two prime numbers x and y is 10, where x > y, then the value of 2x + y is

A. 7
B. 9
C. 11
D. 12
E. 21

LCM (x,y) = 10 and both x an y are prime.
The only values of x and y can be 5 and 2 (x = 5 and y = 2)

2x + y = 2*5 + 2 = 12

Correct Option: D
User avatar
stonecold
Joined: 12 Aug 2015
Last visit: 09 Apr 2024
Posts: 2,248
Own Kudos:
Given Kudos: 893
GRE 1: Q169 V154
GRE 1: Q169 V154
Posts: 2,248
Kudos: 3,472
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Excellent Question.
Here is what i did on this one ->
Since x,y are primes and x>y---->
LCM(x,y) => Product of x*y

Hence 10=xy
10=> 2*5

Thus x=5 ans y=2

So 2x+y=> 12

SMASH THAT D
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 13 May 2024
Posts: 6,755
Own Kudos:
34,142
 [1]
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,755
Kudos: 34,142
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
If the least common multiple of two prime numbers x and y is 10, where x > y, then the value of 2x + y is

A. 7
B. 9
C. 11
D. 12
E. 21

2 and 5 are the only PRIME numbers with an LCM of 10
Since we're told x > y, we can conclude that x = 5 and y = 2

So, 2x + y = 2(5) + 2 = 12

Answer: D

Cheers,
Brent
User avatar
BrushMyQuant
Joined: 05 Apr 2011
Last visit: 20 July 2025
Posts: 2,253
Own Kudos:
Given Kudos: 100
Status:Tutor - BrushMyQuant
Location: India
Concentration: Finance, Marketing
Schools: XLRI (A)
GMAT 1: 700 Q51 V31
GPA: 3
WE:Information Technology (Computer Software)
Expert
Expert reply
Schools: XLRI (A)
GMAT 1: 700 Q51 V31
Posts: 2,253
Kudos: 2,468
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Theory: If two numbers are co-prime (have no common factor apart from 1) then their LCM = product of those numbers

If the least common multiple of two prime numbers x and y is 10
Simce x and y are prime so they will have only one common factor between them which is 1
=> x and y are co-prime numbers
So, LCM(x,y) = x*y = 10
So, x and y can be 2 and 5
But we know that x > y
=> x= 5 and y =2

2x + y = 2*5 + 2 = 12

So, Answer will be D
Hope it helps!

To learn more about LCM and GCD watch these videos



User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,462
Own Kudos:
Posts: 37,462
Kudos: 1,013
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Math Expert
102633 posts
PS Forum Moderator
700 posts