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

Redeem

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.

★★★★★5.0559 reviews
Vote for Target Test Prep, Newsweek Readers’ Choice Awards 2026
NEWSWEEK READERS’ CHOICE 2026

BIG NEWS! Target Test Prep has been nominated, and they’d love your vote!

TTP has worked incredibly hard to build the best test prep experience possible, and winning Newsweek’s 2026 Readers’ Choice Award for Best Test Prep would mean a lot to them. If TTP has helped you, they’d be incredibly grateful for your vote. You can vote once each day through September 9.

Vote for TTP
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
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
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start 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

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

Please explain

Expert replies
Source: — Data Sufficiency |

by linkinpark » Thu Feb 11, 2010 6:25 am
mgmt_gmat wrote:n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number consider 43,52..they satisfy but 98(sum of digits = 17 a prime) > 80 so ignore a
b. Each of the two digits of n is a prime number a little tricky but I pick b, why? because each of digit if prime
the numbers will be like 57, 75, 73, 37,25,52... these will be <80, for rest of numbers from 79 till 99 either 1 or both digits will not be prime hence B is sufficient

OA later
530->480->580
when posting a question don't post OA(even masked) before some discussion.
Join the discussion

by mohit11 » Thu Feb 11, 2010 7:16 am
Tricky question,

n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number
b. Each of the two digits of n is a prime number


A) Not sufficient, 83 > 80, 38 <80


B) Since each of the two digits are a prime number, therefore, we can only consider 2, 3, 5, 7 and the largest number formed using these digits will be 77 which is less than 80, so B


But since you already knew this, i am guessing the answer is not B. Whats the OA?
Join the discussion

by mohit11 » Thu Feb 11, 2010 7:18 am
Oh i thought Linkingpark was mgmt_gmat, Apologies, OA please
Join the discussion

by ajith » Thu Feb 11, 2010 8:52 am
mgmt_gmat wrote:n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number
b. Each of the two digits of n is a prime number

OA later
Prime number between 10-100 are
11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97

a) insufficient - (83 and 61) both have sum of digits as prime numbers
b) 23,37,29,53 and 73 follow this; all of them are under 80 hence n<80; sufficient

B
Always borrow money from a pessimist, he doesn't expect to be paid back.
Join the discussion

by sars72 » Thu Feb 11, 2010 11:01 am
ajith wrote:
mgmt_gmat wrote:n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number
b. Each of the two digits of n is a prime number

OA later
Prime number between 10-100 are
11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97

a) insufficient - (83 and 61) both have sum of digits as prime numbers
b) 23,37,29,53 and 73 follow this; all of them are under 80 hence n<80; sufficient
B
statement 1 only says that the sum of the digits is a prime number. You seem to have mistaken it as "n is a prime number and sum of digits is also prime number". So, from statement 1, the possibilites are not limited to 83 n 61 coz n need not be prime.
Join the discussion

by ajith » Thu Feb 11, 2010 11:08 am
sars72 wrote: statement 1 only says that the sum of the digits is a prime number. You seem to have mistaken it as "n is a prime number and sum of digits is also prime number". So, from statement 1, the possibilites are not limited to 83 n 61 coz n need not be prime.
Well technically it doesn't matter what I thought, it is a perfectly valid combination (83 and 61)to disprove the contention that we can determine whether the number is less than or greater than 80. One of the number is more than 80 and the other is less than 80.

We need only 1 example to disprove a contention, to prove it 1 example would not be sufficient. Possibilities are not limited to 83 and 61, I agree, but, I just needed one example and it works out perfectly well. Nowhere do I mention that, it is the only combination possible
Always borrow money from a pessimist, he doesn't expect to be paid back.
Join the discussion