GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 13 Aug 2018, 23:42

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

PS Squares

Author Message
Manager
Joined: 04 Sep 2008
Posts: 233
Location: Kolkata
Schools: La Martiniere for Boys

Show Tags

08 Jun 2009, 23:34
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

1² - 2² + 3² - 4² + ________ - 10² = ?

A. 45

B. - 45

C. - 54

D. - 55

Doea anyone have the proper techinique of solving this

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________

Thanks
rampuria

Director
Joined: 03 Jun 2009
Posts: 755
Location: New Delhi
WE 1: 5.5 yrs in IT

Show Tags

08 Jun 2009, 23:40
2
=(1-2)(1+2) + (3-4)(3+4) + ...... (7-8)(7+8) + (9-10)(9+10)
= -3 -7 - 11 - 15 - 19
= -55

Hence E
_________________
Intern
Joined: 27 May 2009
Posts: 36

Show Tags

09 Jun 2009, 02:42
rampuria wrote:
1² - 2² + 3² - 4² + ________ - 10² = ?

A. 45

B. - 45

C. - 54

D. - 55

Doea anyone have the proper techinique of solving this

since 1² - 2² = -(1+2)
so the total can be :
-(1+2+3+...10)
which can be calculated by the formula(some of arithmatic progression )
-(n(n+1)/2) for n=10
so it's -55 and hence D.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: PS Squares &nbs [#permalink] 09 Jun 2009, 02:42
Display posts from previous: Sort by

Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne 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®.