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 →

HCF

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
Legendary Member
Posts: 1035
Joined: Wed Aug 27, 2008 10:56 pmFollowed by: 1 member
Thanked: 104 times

by scoobydooby » Sun Jun 06, 2010 8:33 am
1)=> j and k are consecutive integers. the GCF of two consecutive integers is 1. sufficient
2) if j=k=10, GCF=10; if j=3 and k=5, GCF is 1. no unique CF obtained. not sufficient.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 amFollowed by: 2 members
Thanked: 173 times
GMAT Score:710

by gmatmachoman » Mon Jun 07, 2010 3:58 am
scoobydooby wrote:1)=> j and k are consecutive integers. the GCF of two consecutive integers is 1. sufficient
2) if j=k=10, GCF=10; if j=3 and k=5, GCF is 1. no unique CF obtained. not sufficient.

Tip 1: when 2 numbers have GCD as 1, its called co -primes!

Pick A!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 147
Joined: Tue Aug 25, 2009 7:57 pmFollowed by: 17 members
Location: New York City
Thanked: 76 times
GMAT Score:770

by Rich@VeritasPrep » Mon Jun 07, 2010 5:24 am
For clarification as to why two consecutive integers must have a GCF of 1:

If the GCF of two different numbers were 2, for example, both numbers would be even, and thus at least a distance of 2 apart.

If the GCF of two different numbers were 3, both numbers would be multiples of 3, and thus at least a distance of 3 apart.

So in general, if the GCF of two different numbers were N, both numbers would be multiples of N, and thus at least a distance of N apart.

Therefore, if two numbers are consecutive integers (and thus a distance of 1 apart), they cannot have a GCF of anything higher than 1.
Rich Zwelling
GMAT Instructor, Veritas Prep
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1