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
GMATLiveTeach Starts Oct 17
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Chris Peckover, 100th-Percentile GMAT Scorer

Oct 17 · Chris Peckover
Sat · 11:00 AM to 2:00 PM ET
Oct 20 · Chris Peckover
Tue, Thu · 8:00 to 10:00 PM ET
Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 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 559 reviewsTarget Test Prep

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

Multiple of 5 and 125. x=a^2*b?

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
User avatar
Junior | Next Rank: 30 Posts
Posts: 24
Joined: Thu Dec 23, 2010 11:13 pm
Location: India
GMAT Score:640

by nk_81 » Fri Feb 11, 2011 10:21 pm
Can someone show me the approach to this problem?
NK
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

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 » Fri Feb 11, 2011 10:39 pm
If X is a multiple of 5, then either a^2 or b or both are multiples of 5.
Let us solve by example.
Now, 80 = 4^2 * 5. So let a = 4, b = 5, X = 80.
So, 80 is a multiple of 5.
Now ab = 20 is not a multiple of 125.
a *b^2 = 4 * 5^2 = 100 is not a multiple of 125.
a^2 * b^2 = 4^2 * 5^2 = 400 is not a multiple of 125.
a^3 * b^3 = 4^3 * 5^3 = 64 * 125, which is a multiple of 125.
2ab is 2*4*5 = 40 which is not a multiple of 125.

The correct answer is hence 4).
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
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 13
Joined: Sat Feb 05, 2011 10:39 pm
Location: Bangalore, India

by banibhusan » Sat Feb 12, 2011 11:56 am
I took a different approach. Since X is a multiple of 5, so we can conclude that either a or b or both (since a & b are integers, a can't take the value of 5^1/2 in which case a^2 would be a multiple of 5) is a multiple of 5. In case of a^2, assuming that 5 appears in the list of factors of 'a' at least once we can can make sure that its divisible by 125, i.e. 5^3, by multiplying it by simply another 'a'. So it becomes a^3 and its certain to be divisible by 125.

Similarly in case of b, assuming that 5 appears in the list of factors of 'b' at least once, we can multiply it by b^2 to increase the no of '5' factors to 3.

So a^3*b^3 is the answer. I hope I am clear. :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1