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

Multiples

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 125
Joined: Mon Dec 15, 2008 9:24 pm
by joyseychow » Thu Aug 13, 2009 8:06 pm
If n is a multiple of 5, n=p^2q, where p and q are prime numbers. Which of the following must be a multiple of 25?

A. p^2
B. q^2
C. pq
D. p^2q^2
E. p^3q


Easy one, but I didn't get right. Why B cannot be the answer?
Top
Join the discussion
Source: — Problem Solving |
Legendary Member
Posts: 752
Joined: Sun May 17, 2009 11:04 pm
Location: Tokyo
Thanked: 81 times
GMAT Score:680

by tohellandback » Thu Aug 13, 2009 8:45 pm
answer is D
n=p^2q
either p or q can be 5
clearly P^2*q^2 must be divisible by 25.

B cannot be the answer because
if p is 5 then q can be any prime number. 3,7, etc.
in that case p^2 will not be divisible by 25
The powers of two are bloody impolite!!
Top
Join the discussion
Senior | Next Rank: 100 Posts
Posts: 59
Joined: Mon Jul 13, 2009 8:58 pm
Thanked: 10 times
GMAT Score:710

by ankitns » Fri Aug 14, 2009 5:33 am
tohellandback wrote:answer is D
n=p^2q
either p or q can be 5
clearly P^2*q^2 must be divisible by 25.

B cannot be the answer because
if p is 5 then q can be any prime number. 3,7, etc.
in that case p^2 will not be divisible by 25

q cannot be 5...plug in the numbers...if p = 2 and q = 5...we get
n = 2^10 = 1024..not a multiple of 5....

n can only be a multiple of 5 only if p is 5...and if p is a multiple of 5 then p^2 must be a multiple of 25...

Hence the answer is A[spoiler][/spoiler]
Attempt 1: 710, 92% (Q 42, 63%; V 44, 97%)
Attempt 2: Coming soon!
Top
Join the discussion
Legendary Member
Posts: 752
Joined: Sun May 17, 2009 11:04 pm
Location: Tokyo
Thanked: 81 times
GMAT Score:680

by tohellandback » Fri Aug 14, 2009 5:40 am
ankitns wrote:
tohellandback wrote:answer is D
n=p^2q
either p or q can be 5
clearly P^2*q^2 must be divisible by 25.

B cannot be the answer because
if p is 5 then q can be any prime number. 3,7, etc.
in that case p^2 will not be divisible by 25

q cannot be 5...plug in the numbers...if p = 2 and q = 5...we get
n = 2^10 = 1024..not a multiple of 5....

n can only be a multiple of 5 only if p is 5...and if p is a multiple of 5 then p^2 must be a multiple of 25...

Hence the answer is A[spoiler][/spoiler]
with p=2, how r u getting n=2^10
it will be n=2^2*5
..or hey may be you think its n=P^(2q)
The powers of two are bloody impolite!!
Top
Join the discussion
Senior | Next Rank: 100 Posts
Posts: 59
Joined: Mon Jul 13, 2009 8:58 pm
Thanked: 10 times
GMAT Score:710

by ankitns » Fri Aug 14, 2009 7:22 am
yes..I was thinking n=p^(2q)...

joyseychow: Could you please clarify whether the question states

n=p^(2q)

or

n=(p^2) * q


Thanks.

tohellandback wrote:
ankitns wrote:
tohellandback wrote:answer is D
n=p^2q
either p or q can be 5
clearly P^2*q^2 must be divisible by 25.

B cannot be the answer because
if p is 5 then q can be any prime number. 3,7, etc.
in that case p^2 will not be divisible by 25

q cannot be 5...plug in the numbers...if p = 2 and q = 5...we get
n = 2^10 = 1024..not a multiple of 5....

n can only be a multiple of 5 only if p is 5...and if p is a multiple of 5 then p^2 must be a multiple of 25...

Hence the answer is A[spoiler][/spoiler]
with p=2, how r u getting n=2^10
it will be n=2^2*5
..or hey may be you think its n=P^(2q)
Attempt 1: 710, 92% (Q 42, 63%; V 44, 97%)
Attempt 2: Coming soon!
Top
Join the discussion
Master | Next Rank: 500 Posts
Posts: 125
Joined: Mon Dec 15, 2008 9:24 pm

by joyseychow » Sun Aug 23, 2009 2:00 am
ankitns wrote:yes..I was thinking n=p^(2q)...

joyseychow: Could you please clarify whether the question states

n=p^(2q)

or

n=(p^2) * q


Thanks.

tohellandback wrote:
ankitns wrote:
tohellandback wrote:answer is D
n=p^2q
either p or q can be 5
clearly P^2*q^2 must be divisible by 25.

B cannot be the answer because
if p is 5 then q can be any prime number. 3,7, etc.
in that case p^2 will not be divisible by 25

q cannot be 5...plug in the numbers...if p = 2 and q = 5...we get
n = 2^10 = 1024..not a multiple of 5....

n can only be a multiple of 5 only if p is 5...and if p is a multiple of 5 then p^2 must be a multiple of 25...

Hence the answer is A[spoiler][/spoiler]
with p=2, how r u getting n=2^10
it will be n=2^2*5
..or hey may be you think its n=P^(2q)
Sorry. It's n=(p^2) * q.
Top
Join the discussion
Legendary Member
Posts: 527
Joined: Thu May 01, 2008 12:06 am
Thanked: 7 times

by real2008 » Mon Aug 24, 2009 11:05 am
joyseychow wrote:
ankitns wrote:yes..I was thinking n=p^(2q)...

joyseychow: Could you please clarify whether the question states

n=p^(2q)

or

n=(p^2) * q


Thanks.

tohellandback wrote:
ankitns wrote:
tohellandback wrote:answer is D
n=p^2q
either p or q can be 5
clearly P^2*q^2 must be divisible by 25.

B cannot be the answer because
if p is 5 then q can be any prime number. 3,7, etc.
in that case p^2 will not be divisible by 25

q cannot be 5...plug in the numbers...if p = 2 and q = 5...we get
n = 2^10 = 1024..not a multiple of 5....

n can only be a multiple of 5 only if p is 5...and if p is a multiple of 5 then p^2 must be a multiple of 25...

Hence the answer is A[spoiler][/spoiler]
with p=2, how r u getting n=2^10
it will be n=2^2*5
..or hey may be you think its n=P^(2q)
Sorry. It's n=(p^2) * q.
then answer is D
Top
Join the discussion