Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 22 May 2017, 18:02

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# To calculate

Author Message
Intern
Joined: 13 Feb 2009
Posts: 21
Followers: 1

Kudos [?]: 2 [1] , given: 0

### Show Tags

24 Feb 2009, 03:20
1
KUDOS
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

What is value of
1 - 1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42 - 1/56 ?
A. 1/7
B. 1/6
C. 1/8
D. 1/9
E. 1/10
SVP
Joined: 07 Nov 2007
Posts: 1806
Location: New York
Followers: 37

Kudos [?]: 930 [1] , given: 5

### Show Tags

24 Feb 2009, 07:36
1
KUDOS
matematikconsultant wrote:
What is value of
1 - 1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42 - 1/56 ?
A. 1/7
B. 1/6
C. 1/8
D. 1/9
E. 1/10

(1 - 1/2) - (1/6+1/12) - (1/20+1/30) - (1/42+1/56)
=(1/2 - 1/4) - 1/12 - 1/24
=1/4 -1/8
=1/8
_________________

Smiling wins more friends than frowning

VP
Joined: 05 Jul 2008
Posts: 1409
Followers: 39

Kudos [?]: 388 [0], given: 1

### Show Tags

24 Feb 2009, 14:21
initially thought of LCM but quickly noticed that subtracting 1/6 from 1/2 gave 1/3 and then subtracting 1/12 gave 1/4

So the answer would be 1/8
Manager
Joined: 26 Dec 2008
Posts: 58
Schools: Booth (Admit R1), Sloan (Ding R1), Tuck (R1)
Followers: 2

Kudos [?]: 13 [0], given: 0

### Show Tags

24 Feb 2009, 18:45
x2suresh wrote:
matematikconsultant wrote:
What is value of
1 - 1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42 - 1/56 ?
A. 1/7
B. 1/6
C. 1/8
D. 1/9
E. 1/10

(1 - 1/2) - (1/6+1/12) - (1/20+1/30) - (1/42+1/56)
=(1/2 - 1/4) - 1/12 - 1/24
=1/4 -1/8
=1/8

great approach, hats off to you. I am a newbie to the forum and have seen your posts in last 2-3 days -- you rock man!
Intern
Joined: 07 Oct 2008
Posts: 12
Followers: 0

Kudos [?]: 3 [0], given: 0

### Show Tags

24 Feb 2009, 19:40
I am a new person on the form..

1-1/2-1/6-1/12-1/20-1/30-1/42-1/56
=>1/2-1/4-1/12-1/24
3/24=1/8
Intern
Joined: 13 Feb 2009
Posts: 21
Followers: 1

Kudos [?]: 2 [1] , given: 0

### Show Tags

25 Feb 2009, 03:46
1
KUDOS
1- (1-1/2) - (1/2-1/3) - (1/3-1/4) - (1/4-1/5) - (1/5-1/6) -(1/6-1/7) - (1/7-1/8) = 1/8
Manager
Joined: 01 Jan 2008
Posts: 223
Schools: Booth, Stern, Haas
Followers: 2

Kudos [?]: 58 [0], given: 2

### Show Tags

25 Feb 2009, 05:57
matematikconsultant wrote:
1- (1-1/2) - (1/2-1/3) - (1/3-1/4) - (1/4-1/5) - (1/5-1/6) -(1/6-1/7) - (1/7-1/8) = 1/8

I understood the approach you used, but how it helps to make it easier to solve?

thanks

Last edited by kbulse on 25 Feb 2009, 08:45, edited 1 time in total.
Intern
Joined: 13 Feb 2009
Posts: 21
Followers: 1

Kudos [?]: 2 [0], given: 0

### Show Tags

25 Feb 2009, 06:37
Always, 1/(n(n+1)) = 1/n - 1/(n+1)
Re: To calculate   [#permalink] 25 Feb 2009, 06:37
Display posts from previous: Sort by