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

Sum of positive integers

Expert replies
by piyush_nitt » Fri May 08, 2009 5:44 am
Sum of positive integers x and y is 72. What is xy?
a. x = y + 1
b. x and y have same tens digit
Join the discussion
Source: — Data Sufficiency |

by DanaJ » Fri May 08, 2009 10:30 am
This problem is wrong.
Statement 1 doesn't make sense and let me explain why. x and y are both positive integers and it says there that x = y + 1. Since x + y = 72, then it's safe to say that y + 1 + y = 2y + 1 = 72. This means that 2y = 71, with y = 35.5. As you can see, 35.5 is NOT a positive integer. This contradicts the initial assumption.
Join the discussion

Re: Sum of positive integers

by Ian Stewart » Fri May 08, 2009 2:36 pm
piyush_nitt wrote:Sum of positive integers x and y is 72. What is xy?
a. x = y + 1
b. x and y have same tens digit
Agree with Dana - if x+y = 72, then either x and y are both odd, or x and y are both even. Statement 1 says that x and y are consecutive integers (i.e. one of them is odd, the other even) which contradicts information in the question.

If S1 didn't lead to a contradiction (e.g. if it said x = y+2), using it and the information in the question, you'd be able to find both x and y, and therefore answer the question. S2 alone would not be sufficient, since there are a few pairs of values of x and y with the same tens digit that add to 72 (36+36, 35+37, etc), and for each we get a different product xy.

Still, if that's the original version of the question, there's something wrong with the source.
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
Join the discussion