Find all School-related info fast with the new School-Specific MBA Forum

It is currently 27 Jul 2014, 22:34

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Decimal Fraction

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
User avatar
Status: GMAT Learner
Joined: 14 Jul 2010
Posts: 653
Followers: 33

Kudos [?]: 192 [0], given: 32

GMAT Tests User
Decimal Fraction [#permalink] New post 23 Feb 2011, 07:52
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

71% (01:36) correct 29% (00:30) wrong based on 7 sessions
If t= 1/2^9x5^3 is expressed as a terminating decimal, how many zeros will t have between the decimal point and the first nonzero digit to the right of the decimal point/
a. three
b. four
c. five
d. six
c. nine

suggest shortest and easier approach please.
[Reveal] Spoiler: OA

_________________

I am student of everyone-baten
Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

4 KUDOS received
Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 2048
Followers: 126

Kudos [?]: 880 [4] , given: 376

GMAT Tests User
Re: Decimal Fraction [#permalink] New post 23 Feb 2011, 08:12
4
This post received
KUDOS
t= \frac{1}{2^9 * 5^3}

t= \frac{1}{2^6 * 2^3 * 5^3}

t= \frac{1}{2^6 * (2*5)^3}

t= \frac{1}{64 * (10)^3}

Multiplying numerator and denominator by 10^2

t= \frac{10^2}{64 * (10)^5}

t= \frac{1.something}{(10)^5}

t= 1.something * 10^{-5}

To remove 10^{-5} we need to move decimal point 5 digits to the left

t= .00001something

4 zeros between decimal and first non-zero digit.

Ans: "B"
_________________

~fluke

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
User avatar
Joined: 17 Feb 2011
Posts: 201
Concentration: Real Estate, Finance
Schools: MIT (Sloan) - Class of 2014
GMAT 1: 760 Q50 V44
Followers: 30

Kudos [?]: 474 [0], given: 70

GMAT Tests User
Re: Decimal Fraction [#permalink] New post 23 Feb 2011, 12:30
I think there is no easier way than this.

fluke wrote:
t= \frac{1}{2^9 * 5^3}

t= \frac{1}{2^6 * 2^3 * 5^3}

t= \frac{1}{2^6 * (2*5)^3}

t= \frac{1}{64 * (10)^3}

Multiplying numerator and denominator by 10^2

t= \frac{10^2}{64 * (10)^5}

t= \frac{1.something}{(10)^5}

t= 1.something * 10^{-5}

To remove 10^{-5} we need to move decimal point 5 digits to the left

t= .00001something

4 zeros between decimal and first non-zero digit.

Ans: "B"
SVP
SVP
avatar
Joined: 16 Nov 2010
Posts: 1692
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 30

Kudos [?]: 275 [0], given: 36

GMAT Tests User Premium Member Reviews Badge
Re: Decimal Fraction [#permalink] New post 23 Feb 2011, 20:46
1/1000 * 1/2^6 = 5^6/5^6 * 1/2^6 * 1/1000 = 5^6/10^9 = 5 digits/10^9

=> Answer is B (4 zeroes)
_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Expert Post
1 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4587
Location: Pune, India
Followers: 1034

Kudos [?]: 4507 [1] , given: 162

Re: Decimal Fraction [#permalink] New post 30 Mar 2011, 18:52
1
This post received
KUDOS
Expert's post
What fluke did above is great. Let me just add here that if you are stuck with how to proceed, don't shy away from quick and easy calculations.

\frac{1}{2^9*5^3} = \frac{1}{2^6*1000}

Now, I can divide 1 by 64 to get the decimal point: .01

If I divide this further by 1000, the decimal moves 3 places to the left and I get four 0s before the 1.

Sometimes, under pressure in the exam, Math will fail you. Go with your instincts and use logic. (Except if your instincts tell you to multiply a four digit number with a five digit number - then you are definitely missing the point!)
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Re: Decimal Fraction   [#permalink] 30 Mar 2011, 18:52
    Similar topics Author Replies Last post
Similar
Topics:
1 Experts publish their posts in the topic Convert decimal to fraction GMATD11 4 31 Jan 2011, 20:25
fractions to decimals bhuvana 0 20 Nov 2010, 00:38
1 Recurring decimal to fraction srivicool 1 08 Sep 2010, 09:12
converting decimals to fractions niquebeats 1 25 Feb 2010, 01:15
Fractions/Decimals/Percents above720 6 17 Aug 2007, 16:43
Display posts from previous: Sort by

Decimal Fraction

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.