Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 563 reviewsTarget Test Prep

Greatest common factor

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 75
Joined: Fri Jan 16, 2009 2:00 pm
Thanked: 1 times
GMAT Score:550
by jfranco23 » Fri Mar 13, 2009 4:53 pm
What is the greatest common factor of the positive integers j and k?

1. k=j+1
2. jk is divisible by 5
Top
Join the discussion
Source: — Data Sufficiency |
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members
Thanked: 331 times

by cramya » Fri Mar 13, 2009 5:40 pm
Stmt II

j=5 k=5 (j and k can be equal no where its given it cant be)

gcf = 5

j=2 k=5

gcf=1

INSUFF


Stmt I

k = j+1

Either k is odd j is even or j is odd k is even which means only 1 can be the greatest common factor

SUFF

Choose A
Top
Join the discussion

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2623
Joined: Mon Jun 02, 2008 3:17 amFollowed by: 355 members
Location: Montreal
Thanked: 1090 times
GMAT Score:780

by Ian Stewart » Fri Mar 13, 2009 6:01 pm
cramya wrote: Stmt I

k = j+1

Either k is odd j is even or j is odd k is even which means only 1 can be the greatest common factor

SUFF
It's not that one of the numbers is even and one odd that makes the GCD equal to 1 here -- after all, 12 is even, and 15 is odd, but their GCD is not 1 -- it's the fact that the numbers are consecutive. The GCD of consecutive integers x and x+1 is always equal to 1, since if d is a divisor of x, then x+d will be the closest multiple of d which is larger than x, so d couldn't be a divisor of x+1 unless d=1.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Top
Join the discussion
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members
Thanked: 331 times

by cramya » Fri Mar 13, 2009 6:14 pm
Thanks Ian!
Top
Join the discussion