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

It is currently 22 Jul 2014, 07:45

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

Tips and Tricks

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
avatar
Joined: 25 Jun 2009
Posts: 313
Followers: 2

Kudos [?]: 70 [0], given: 6

GMAT Tests User
Tips and Tricks [#permalink] New post 28 Jul 2009, 04:10
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions
I was wondering if there are any tips or tricks to save time in questions like these rather than manually calculating values. I know one trick which is used to check the greater values in fractions

For e.g to check which one greater among say 2/3 , 3/16 and 7/ 48

Just multiply the denominator one fraction to other numerator i.e 2 x 16 and 3 x 3. here 2x16 is greater hence the 2/3 is greater than 3/16.

Folks please share if you know tips and tricks to save time while doing these cheesy time consuming calculations.

Thanks
Attachments

untitled.JPG
untitled.JPG [ 18.55 KiB | Viewed 2991 times ]

9 KUDOS received
Manager
Manager
User avatar
Joined: 03 Jul 2009
Posts: 107
Location: Brazil
Followers: 2

Kudos [?]: 47 [9] , given: 13

GMAT Tests User
Re: Tips and Tricks [#permalink] New post 28 Jul 2009, 12:16
9
This post received
KUDOS
I have taken 15 seconds to resolve this problem! For this problem specifically, there are some very fast tricks that you can do remembering the properties of recurring decimals. You just need a little patience to understand a first time. Then you probably will never forget.

Here is a brief description useful in a some GMAT exercises:

First - We use the number that is repeating and the denominator has as many "9" digits as there are different digits in the block that repeats. e.g.
0.555555 = 5/9
0.13131313 = 13/99
0.432432432432 = 432/999

Second - If the sequence starts to repeat after some zeros, add the same number of zeros in the denominator. e.g.
0.005555 = 5/900
0.013131313 = 13/990
0.0004324324324... = 432/999000 = 54/124875 = 2/4625

Third - Terminating decimals + Repeating Decimals. e.g.
2.31555555 = 2.31 + 0.00555555 = 231/100 + 5/900
0.745454545 = 0.7 + 0.0454545 = 7/10 + 45/990

Last one - The reciprocal of a prime number "p", except 2 and 5, has a repeating sequence of p-1 digits, or a factor of p-1 digits. e.g.
1/7 = 0.142857 142857 142857... - As you can notice, the sequence has 6 digits = p-1 = 7-1 = 6 digits.
And if you multiply this fraction by a number you will only change the beginning of the sequence. e.g.
4/7 = 4*1/7 = 0.57 142857 142857 ...

****************
Once you have all these little rules in mind it is very fast to work in this problem.
A) 2/11 -> 11 is a factor of 99, so there are 2 repeating digits.
B) 1/3 -> 3 is a factor of 9, so there is 1 repeating digit.
C) 41/99 -> 99, so there are 2 repeating digits.
D) 2/3 -> 3 is a factor of 9, so there is 1 repeating digit..
E) 23/37 -> As I still don't have one item that is winning in repeating digits, this must be CORRECT

E

Good studies!

If you enjoyed the post, please consider a kudo!!! ;) I need to practice my verbal skills in the GMATClub tests :)

Last edited by coelholds on 28 Jul 2009, 13:55, edited 2 times in total.
1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 25 Jun 2009
Posts: 313
Followers: 2

Kudos [?]: 70 [1] , given: 6

GMAT Tests User
Re: Tips and Tricks [#permalink] New post 28 Jul 2009, 12:25
1
This post received
KUDOS
coelholds wrote:
I have taken 15 seconds to resolve this problem! For this problem specifically, there are some very fast tricks that you can do remembering the properties of recurring decimals. You just need a little patience to understand a first time. Then you probably will never forget.

Here is a brief description useful in a some GMAT exercises:

First - We use the number that is repeating and the denominator has as many "9" digits as there are different digits in the block that repeats. e.g.
0.555555 = 5/9
0.13131313 = 13/99
0.432432432432 = 432/999

Second - If the sequence starts to repeat after some zeros, add the same number of zeros in the denominator. e.g.
0.005555 = 5/900
0.013131313 = 13/990
0.0004324324324... = 432/999000 = 54/124875 = 2/4625

Third - Terminating decimals + Repeating Decimals. e.g.
2.31555555 = 2.31 + 0.00555555 = 231/100 + 5/900
0.745454545 = 0.7 + 0.0454545 = 7/10 + 45/990

Last one - The reciprocal of a prime number "p", except 2 and 5, has a repeating sequence of p-1, or a multiple of p-1. e.g.
1/7 = 0.142857 142857 142857... - As you can notice, the sequence has 6 digits = p-1 = 7-1 = 6 digits.
And if you multiply this fraction by a number you will only change the beginning of the sequence. e.g.
4/7 = 4*1/7 = 0.57 142857 142857 ...

****************
Once you have all these little rules in mind it is very fast to work in this problem.
A) 2/11 -> 11 is a factor of 99, so there are 2 repeating digits.
B) 1/3 -> 3 is a factor of 9, so there is 1 repeating digit.
C) 41/99 -> 99, so there are 2 repeating digits.
D) 2/3 -> 3 is a factor of 9, so there is 1 repeating digit..
E) 23/37 -> As I still don't have one item that is winning in repeating digits, this must be CORRECT

E

Good studies!

If you enjoyed the post, please consider a kudo!!! ;) I need to practice my verbal skills in the GMATClub tests :)



Thanks coelholds, That was nice.. ! +1 for this one .. without knowing these tricks I spent almost 1.5 min.
2 KUDOS received
Manager
Manager
User avatar
Joined: 03 Jul 2009
Posts: 107
Location: Brazil
Followers: 2

Kudos [?]: 47 [2] , given: 13

GMAT Tests User
Re: Tips and Tricks [#permalink] New post 29 Jul 2009, 05:25
2
This post received
KUDOS
You are welcome and thanks ;)
Senior Manager
Senior Manager
avatar
Joined: 16 Apr 2009
Posts: 252
Schools: Ross
Followers: 1

Kudos [?]: 18 [0], given: 10

GMAT Tests User
Re: Tips and Tricks [#permalink] New post 29 Jul 2009, 06:25
vivid explanations.
+1 from me..

Please post tips and tricks like these. you'll be flooded with kudos!!!
_________________

Keep trying no matter how hard it seems, it will get easier.

Re: Tips and Tricks   [#permalink] 29 Jul 2009, 06:25
    Similar topics Author Replies Last post
Similar
Topics:
79 Experts publish their posts in the topic Tips and Tricks: Inequalities Zarrolou 26 14 Apr 2013, 08:20
15 CR Tips Tricks and Questions crackHSW 1 12 Aug 2012, 06:18
Tips and tricks; Math selimdu 3 07 Jan 2009, 23:46
Experts publish their posts in the topic Math formulas, tips/tricks venkis 3 06 Feb 2008, 20:46
Display posts from previous: Sort by

Tips and Tricks

  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®.