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

Consecutive integers- faster method anyone? and key idea

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 52
Joined: Sat Aug 13, 2011 8:34 am
Thanked: 2 times
by kaps786 » Sat Aug 13, 2011 11:22 am
Hi

An MGMAT qn, the explanations for which I have seen are fairly elaborate algebra - wondering if anyone has a better approximate method or approach to solve this on real question.

I also did not grasp completely what is the underlying concept/key idea being tested.

Kindly help



If q, r, and s are consecutive even integers and q < r < s, which of the following CANNOT be the value of s2 - r2 - q2?


-20
0
8
12
16

OA follows....

OA 8

Thanks
kaps
Top
Join the discussion
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Sat Aug 13, 2011 12:43 pm
kaps786 wrote:Hi

An MGMAT qn, the explanations for which I have seen are fairly elaborate algebra - wondering if anyone has a better approximate method or approach to solve this on real question.

I also did not grasp completely what is the underlying concept/key idea being tested.

Kindly help



If q, r, and s are consecutive even integers and q < r < s, which of the following CANNOT be the value of s2 - r2 - q2?


-20
0
8
12
16

OA follows....

OA 8

Thanks
kaps
I was able to solve very quickly by plugging in values.

-4,-2,0:
0^2 - (-2)^2 - (-4)^2 = -20.
Eliminate A.

-2,0,2:
2^2 - 0^2 - (-2)^2 = 0.
Eliminate B.

0,2,4:
4^2 - 2^2 - 0^2 = 12.
Eliminate D.

Plugging in 2,4,6 -- or a set of greater consecutive even integers -- will yield a result greater than 12.
No way to yield a result of 8.

The correct answer is C.

For the skeptical:

2,4,6:
6^2 - 4^2 - 2^2 = 16.
Eliminate E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Legendary Member
Posts: 608
Joined: Sun Jun 19, 2011 11:16 amFollowed by: 8 members
Thanked: 37 times

by saketk » Sun Aug 14, 2011 11:52 am
you can do this question like this as well -
let
q= 2a
r= 2a+2
s= 2a+4

where a is an integer number both positive and negative ( -1,0,1,2,3 etc )

now as per the equation given in the question

s2-r2-q2 -- we get,

4a2+16+16a - (4a2+4+8a) - 4a2

or, -4a2+8a+12 --

now, start plugging values,

a=1, gives 16
a=2, gives 12
a=3, gives 0
a=4, gives -20

Therefore, the correct answer is 8.
Top
Join the discussion