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.

★★★★★5.0563 reviews
Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep
NEWSWEEK READERS’ CHOICE AWARDS 2026

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

GMATLiveTeach Starts Oct 25
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

Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 PM ET
Nov 8 · 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
EALiveTeachOnDemand 5 seats left Start anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

165+ EA score guarantee
$05-day trial no automatic billing
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 Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget 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
Start free 5-day trial
Read 563 reviewsTarget Test Prep

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

tricky digits problem: units digit of a three digit number

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 158
Joined: Mon Nov 02, 2009 5:49 pmFollowed by: 3 members
Thanked: 2 times
by tonebeeze » Tue Apr 26, 2011 3:23 pm
Confused. Please help.

If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?

1. The tens digit of k + 9 is 3

2. The tens digit of k + 4 is 2
Top
Join the discussion
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 965
Joined: Thu Jan 28, 2010 12:52 amFollowed by: 34 members
Thanked: 156 times
GMAT Score:720

by vineeshp » Tue Apr 26, 2011 4:44 pm
1) Sufficient.
if unit's digit is non zero, then the number ends with one of 1-9.

If the tens digit of k + 9 is 3, then k+9 is between 30-38.
k is between 21-29.

Hence tens digit is 2.
(even if you take 121,221 etc, the argument still holds good.)

2) Insufficient.
k + 4 has tens digit as 2.

say k ends in 18, then k + 4 would have tens digit 2.
say k ends in 22, then k + 4 would have tens digit 2.

So we cant predict the tens digit of k.
Vineesh,
Just telling you what I know and think. I am not the expert. :)
Top
Join the discussion

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members
Location: Milpitas, CA
Thanked: 1854 times
GMAT Score:770

by Anurag@Gurome » Wed Apr 27, 2011 4:51 am
tonebeeze wrote:Confused. Please help.

If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?

1. The tens digit of k + 9 is 3

2. The tens digit of k + 4 is 2
Let k = XYZ, so that Z is non zero.

(1) The tens digit of k + 9 is 3 implies tens digit of (XYZ + 9) = 3
The minimum digit of Z can be 1 (as it non-zero). Then XY1 + 9 implies the units digit will be 0, with a carry over of 1 to tens place. And since tens digit of k + 9 is 3, so Y = 2.
The maximum digit of Z can be 9. Then XY9 + 9 implies units digit will be 8, with a carry over of 1 to tens place. So, again Y = 2.
So, the tens digit of k is 2.
Hence, (1) is SUFFICIENT.

(2) The tens digit of k + 4 is 2 implies tens digit of (XYZ + 4) = 2
If Z = 2, then (X22 + 4) = X26, here tens digit of k = 2
If Z = 8, then (X18 + 4) = X22, here tens digit of k = 1
We don't get a definite answer.
Hence, (2) is NOT SUFFICIENT.

The correct answer is A.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Join the discussion
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 » Wed Apr 27, 2011 6:14 am
tonebeeze wrote:Confused. Please help.

If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?

1. The tens digit of k + 9 is 3

2. The tens digit of k + 4 is 2
Statement 1: The tens digit of k+9 is 3.
Between 100 and 200:
k+9 could be 130 through 139.
Thus, k could be 130-9 = 121 through 139-9 = 130.
Since the units digit of k must be nonzero, k cannot be 130.
Thus, k = {121...129}.
Using this same logic, between 200 and 300:
k = {221...229}.
And so on.
In every case, the tens digit of k is 2.
Sufficient.

Statement 2: The tens digit of k + 4 is 2.
Between 100 and 200:
k+4 could be 120 through 129.
Thus, k could be 120-4 = 116 through 129-4 = 125 (excluding 120, since the units of k must be nonzero).
Thus, the tens digit of k could be 1 or 2.
Insufficient.

The correct answer is A.
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