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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

GMAT Prep ques.

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 1
Joined: Wed Mar 14, 2007 9:40 am
by MarkIppo » Tue Apr 03, 2007 12:40 pm
This one is probably easy for you guys, but it is stumping me.

5^21 x 4^11=2 x 10^n

Reads: 5 to the 21st power mult. by 4 to the 11th power equals 2 mult by 10 to the nth power. What is n?

I know the answer because I took the practice test, but how does one get there?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 18
Joined: Tue Mar 06, 2007 8:57 am

by gmatme » Tue Apr 03, 2007 1:42 pm
5^21 * 4 ^11 = 2 * 10^n
5 ^21 * (2^2)^11 = 5 ^21 * 2 ^22 = 5 ^21 * 2 ^21 * 2 = 10 ^21 * 2

So n = 21.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Tue Mar 27, 2007 2:53 pm

by vk.neni » Tue Apr 03, 2007 1:43 pm
Reorganizing the following equation a little differently leads us to the answer quite quickly.

5^21 x 4^11=2 x 10^n

5^21 x (2^2)^11 = 2 x 10^n

5^21 x 2^22 = 2 x 10^n

(5x2)^21 x 2 = 2 x 10^n

10^21 = 10^n


So n=21.


-Neni
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 559
Joined: Tue Mar 27, 2007 1:29 amFollowed by: 2 members
Thanked: 5 times

by Cybermusings » Wed Apr 04, 2007 3:57 am
5^21 x 4^11=2 x 10^n

5^21 x (2^2)^11= 2 x 10^n

5^21 x 2^22 = 2 x 10^n

5^21 x 2^21 x 2 = 2 x 10^n

10^21 x 2 = 2 x 10^n

10^21 = 10^n

Thus n = 21
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 222
Joined: Tue Mar 25, 2008 3:52 pm
Thanked: 2 times

by vinviper1 » Mon May 12, 2008 10:34 am
(2^2)^11 = 2^22

Is this a rule of some sort that can be used for all exponents? Thanks.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 400
Joined: Mon Dec 10, 2007 1:35 pm
Location: London, UK
Thanked: 19 times
GMAT Score:680

by II » Mon May 12, 2008 12:08 pm
vinviper1 wrote:(2^2)^11 = 2^22

Is this a rule of some sort that can be used for all exponents? Thanks.
We notice that 4 is a perfect square (i.e. 2^2). So we can rewrite "4^11" as (2^2)^11 ... which is simplified to 2^22.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pmFollowed by: 614 members
Location: Toronto
Thanked: 1710 times
GMAT Score:800

by Stuart@KaplanGMAT » Mon May 12, 2008 1:19 pm
vinviper1 wrote:(2^2)^11 = 2^22

Is this a rule of some sort that can be used for all exponents? Thanks.
Yes:

(x^a)^b = x^(a*b)

e.g.:

(2^5)^3 = 2^(5*3) = 2^15

Similarly:

(x^a) * (x^b) = x^(a+b)

e.g."

(2^5) * (2^3) = 2^(5+3) = 2^8

And:

(x^a) / (x^b) = x^(a-b)

(2^5) / (2^3) = 2^(5-3) = 2^2
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 222
Joined: Tue Mar 25, 2008 3:52 pm
Thanked: 2 times

by vinviper1 » Wed May 14, 2008 8:03 am
Thanks Stuart!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1