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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

Number properties question

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 136
Joined: Wed Apr 08, 2009 12:09 pmFollowed by: 1 member
Thanked: 4 times
by Troika » Tue Apr 10, 2012 5:49 pm
If positive integer x is a multiple of 6 and positive integer y is a multiple of 14, is xy a multiple of 105?

1. x is a multiple of 9
2. y is a multiple of 25

OA: B

#82, OG 12
The only battle you can loose, is the one you abandon.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
User avatar
GMAT Instructor
Posts: 1248
Joined: Thu Mar 29, 2012 2:57 pmFollowed by: 192 members
Location: Everywhere
Thanked: 503 times
GMAT Score:780

by Bill@VeritasPrep » Tue Apr 10, 2012 6:17 pm
To be a multiple of 105, xy must contain the factors 3, 5, and 7. Since x is a multiple of 6, it has factors of 3 and 2. Since y is a multiple of 14, it has factors of 7 and 2. We can see that the 3 and the 7 are already covered; we just need to find a 5 in either x or y.

1. X being a multiple of 9 gives us another 3, but we still don't know for sure if we have a 5; if x=54, then no, but if x=270, then yes. Insufficient.

2. If y is a multiple of 25, it has two 5's as factors. Thus, we have the missing piece that we needed to guarantee that xy is a multiple of 105. Sufficient.
Join Veritas Prep's 2010 Instructor of the Year, Matt Douglas for GMATT Mondays

Visit the Veritas Prep Blog

Try the FREE Veritas Prep Practice Test
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members
Location: Milpitas, CA
Thanked: 1854 times
GMAT Score:770

by Anurag@Gurome » Tue Apr 10, 2012 7:11 pm
HG10 wrote:If positive integer x is a multiple of 6 and positive integer y is a multiple of 14, is xy a multiple of 105?

1. x is a multiple of 9
2. y is a multiple of 25

OA: B

#82, OG 12
x = 2 * 3
y = 2 * 7
105 = 3 * 5 * 7
x * y = 2² * 3 * 7
For xy to be a multiple of 105, we need at least one 3, 5, and 7 among the factors. So, the missing number is 5, as 3 and 7 are already there.

(1) x is a multiple of 9 but this does not imply anything about the missing factor, 5; NOT sufficient.

(2) y is a multiple of 25 and 25 = 5 * 5, which answers the question; SUFFICIENT.

The correct answer is B.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 287
Joined: Fri Mar 23, 2012 12:33 amFollowed by: 6 members
Location: Pune,India
Thanked: 60 times

by GMAT Kolaveri » Tue Apr 10, 2012 7:35 pm
x = 6,12,18 .... 3 x 2
y = 14,28....... 7 x 2

105 = 5 x 7 x 3 ( we need atleast one 5, one 7 AND one 3 to show xy is a multiple of 105)

xy= 3 x 7 x 2 x 2 ( we need a 5) in analyzing we see that 5 is present in B. hence ans could be B or D.

To prove AO is NOT D, we see that A gives 3 which we ve already know. hence D is wrong.
AO: B

Key to this is knowing PRIME FACTORIZATION
Regards and Thanks,
Vinoth@GMAT Kolaveri
https://www.facebook.com/GmatKolaveri
https://gmatkolaveri.tumblr.com/

Click the thank you button if you like my reply :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 136
Joined: Wed Apr 08, 2009 12:09 pmFollowed by: 1 member
Thanked: 4 times

by Troika » Wed Apr 11, 2012 6:53 am
Guys, thank you for the solutions. Those were very helpful!
The only battle you can loose, is the one you abandon.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1