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

It is currently 21 Oct 2014, 07:53

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

What is the sum of the multiples of 7 from 84 to 140, inclus

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
2 KUDOS received
Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 169 [2] , given: 33

What is the sum of the multiples of 7 from 84 to 140, inclus [#permalink] New post 23 May 2007, 19:47
2
This post received
KUDOS
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

73% (02:13) correct 27% (01:18) wrong based on 179 sessions
What is the sum of the multiples of 7 from 84 to 140, inclusive?

A. 896
B. 963
C. 1008
D, 1792
E. 2016
[Reveal] Spoiler: OA

Last edited by Bunuel on 22 Jul 2013, 10:01, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
Director
Director
User avatar
Joined: 26 Feb 2006
Posts: 908
Followers: 4

Kudos [?]: 44 [0], given: 0

Re: PS [#permalink] New post 23 May 2007, 20:35
LM wrote:
What is the sum of the multiples of 7 from 84 to 140, inclusive?
    896
    963
    1008
    1792
    2016


Please explain some FAST SHORT method


= [(140 + 84)/2] [(140/7) - (84/7 + (1)]
= 1008
Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 169 [0], given: 33

Re: PS [#permalink] New post 23 May 2007, 20:55
Himalayan wrote:
LM wrote:
What is the sum of the multiples of 7 from 84 to 140, inclusive?
    896
    963
    1008
    1792
    2016


Please explain some FAST SHORT method


= [(140 + 84)/2] [(140/7) - (84/7 + (1)]
= 1008



Wonderful!!! Thanks a lot!! Could you please explain too?
Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 169 [0], given: 33

Re: PS [#permalink] New post 23 May 2007, 21:00
LM wrote:
Himalayan wrote:
LM wrote:
What is the sum of the multiples of 7 from 84 to 140, inclusive?
    896
    963
    1008
    1792
    2016


Please explain some FAST SHORT method


= [(140 + 84)/2] [(140/7) - (84/7 + (1)]
= 1008



Wonderful!!! Thanks a lot!! Could you please explain too?


Okayyy I got it!! you are using AP series formula!!
Manager
Manager
User avatar
Joined: 13 Feb 2007
Posts: 63
Followers: 1

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

simpler method [#permalink] New post 23 May 2007, 22:57
all you have to do on a quick test like gmat is this:

84, 91, 98, 105, 112, 119, 126, 133, 140.

i wouldn't even list 'em out on the test.

(84 + 140) / 4.5 = answer
Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 169 [0], given: 33

Re: simpler method [#permalink] New post 26 May 2007, 18:17
ethan_casta wrote:
all you have to do on a quick test like gmat is this:

84, 91, 98, 105, 112, 119, 126, 133, 140.

i wouldn't even list 'em out on the test.

(84 + 140) / 4.5 = answer


What is 4.5? Why are you dividing by 4.5 and where did you get that? How do you reach the answer with your method in short time.
Intern
Intern
avatar
Joined: 26 Jun 2012
Posts: 24
Location: Germany
Concentration: Leadership, Finance
GMAT 1: 570 Q31 V39
GMAT 2: 710 Q43 V44
Followers: 0

Kudos [?]: 33 [0], given: 1

GMAT ToolKit User
Re: What is the sum of the multiples of 7 from 84 to 140, [#permalink] New post 22 Jul 2013, 09:57
You could also add up the last digit of the multiples:

4 + 1 + 8 + 5 + 2 + 9 + 6 + 3 + 0 = ..8 --> last digit of solution must be 8 --> 1008 --> Answer C
Intern
Intern
avatar
Joined: 26 Jun 2012
Posts: 24
Location: Germany
Concentration: Leadership, Finance
GMAT 1: 570 Q31 V39
GMAT 2: 710 Q43 V44
Followers: 0

Kudos [?]: 33 [0], given: 1

GMAT ToolKit User
Re: What is the sum of the multiples of 7 from 84 to 140, [#permalink] New post 22 Jul 2013, 09:59
By the way,

Difficulty: 500-600
Tag: Consecutive Integers
Source: Manhattan GMAT
OA:
[Reveal] Spoiler:
Answer C
1 KUDOS received
Intern
Intern
avatar
Joined: 25 May 2012
Posts: 7
Location: United States
Concentration: Finance
WE: Corporate Finance (Non-Profit and Government)
Followers: 0

Kudos [?]: 7 [1] , given: 0

GMAT ToolKit User
Re: What is the sum of the multiples of 7 from 84 to 140, inclus [#permalink] New post 22 Jul 2013, 12:19
1
This post received
KUDOS
The formula we want to use in this type of problem is this:
Average*Total Numbers=Sum

First, find the average by taking the sum of the F + L number and divide it by 2:
A = (F + L)/2

Second, find the total numbers in our range by dividing our F and L numbers by 7 and add 1.
(140/7) - (84/7) + 1

Multiply these together so what we show Average*Total Numbers=Sum
(84 + 140)/2 * (140/7) - (84/7) + 1 = Sum
112 * 9 = 1008
C
Expert Post
5 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4877
Location: Pune, India
Followers: 1152

Kudos [?]: 5348 [5] , given: 165

Re: What is the sum of the multiples of 7 from 84 to 140, inclus [#permalink] New post 22 Jul 2013, 21:44
5
This post received
KUDOS
Expert's post
LM wrote:
What is the sum of the multiples of 7 from 84 to 140, inclusive?

A. 896
B. 963
C. 1008
D, 1792
E. 2016


Alternatively, note that 84 = 7*12 and 140 = 7*20

7*12 + 7*13 + ... 7*20 = 7*(12 + 13 + 14 .. + 20)
12 to 20 are 9 consecutive numbers so their sum will be (middle number) * 9 = 16*9 = 144

Total sum = 7*144 = 1008
_________________

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

1 KUDOS received
Manager
Manager
User avatar
Joined: 22 Apr 2013
Posts: 88
Followers: 1

Kudos [?]: 21 [1] , given: 95

Re: simpler method [#permalink] New post 07 Aug 2013, 06:41
1
This post received
KUDOS
LM wrote:
ethan_casta wrote:
all you have to do on a quick test like gmat is this:

84, 91, 98, 105, 112, 119, 126, 133, 140.

i wouldn't even list 'em out on the test.

(84 + 140) / 4.5 = answer


What is 4.5? Why are you dividing by 4.5 and where did you get that? How do you reach the answer with your method in short time.



It's multiply by 4.5. (84 + 140) * 9/2 == 224*4.5 == 1008 The 9 in the formula is the number of consecutive items in the list.
_________________

I do not beg for kudos.

Senior Manager
Senior Manager
avatar
Joined: 10 Jul 2013
Posts: 343
Followers: 3

Kudos [?]: 120 [0], given: 102

Re: What is the sum of the multiples of 7 from 84 to 140, inclus [#permalink] New post 07 Aug 2013, 09:10
1
This post was
BOOKMARKED
LM wrote:
What is the sum of the multiples of 7 from 84 to 140, inclusive?

A. 896
B. 963
C. 1008
D, 1792
E. 2016


solution;
(140-84)/7 = 8
so total number = 8+1 = 9
summation= 9/2 {2*84+(9-1)*7} = 1008 = C
_________________

Asif vai.....

Intern
Intern
avatar
Joined: 05 Apr 2010
Posts: 15
Followers: 0

Kudos [?]: 7 [0], given: 4

Re: What is the sum of the multiples of 7 from 84 to 140, inclus [#permalink] New post 07 Aug 2013, 09:28
Asifpirlo wrote:
LM wrote:
What is the sum of the multiples of 7 from 84 to 140, inclusive?

A. 896
B. 963
C. 1008
D, 1792
E. 2016


solution;
(140-84)/7 = 8
so total number = 8+1 = 9
summation= 9/2 {2*84+(9-1)*7} = 1008 = C



All perfect till no of terms. I suggest following for sum.
sum = number of terms * (avg of first and last term) = 9 * (84+140)/2 = 1008.

May help save a second or two. :)
Manager
Manager
avatar
Joined: 23 Jan 2013
Posts: 107
Concentration: Technology, Other
Schools: Haas
GMAT Date: 01-14-2015
WE: Information Technology (Computer Software)
Followers: 1

Kudos [?]: 9 [0], given: 22

GMAT ToolKit User CAT Tests
Re: What is the sum of the multiples of 7 from 84 to 140, inclus [#permalink] New post 31 Mar 2014, 10:48
All numbers are consecutive and with a spacing of 7 .

So average would be (140 + 84 )/2 = 112 .

Sum of 9 numbers = 9 * average = 9 * 112 = 1008
Re: What is the sum of the multiples of 7 from 84 to 140, inclus   [#permalink] 31 Mar 2014, 10:48
    Similar topics Author Replies Last post
Similar
Topics:
1 What is the product of the greatest 2 digit multiple of 7 clciotola 4 13 May 2013, 06:13
Is the integer n a multiple of 140 ? (1) n is a multiple of javed 2 20 Apr 2007, 23:06
Is the integer n a multiple of 140 ? (1) n is a multiple of acfuture 5 10 May 2006, 17:09
What is the sum of the integers from 100 to 140 inclusive? hedder02 3 23 Jan 2006, 12:39
What is the sum of the integers from 100 to 140, inclusive? sudhagar 8 17 Oct 2005, 07:39
Display posts from previous: Sort by

What is the sum of the multiples of 7 from 84 to 140, inclus

  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®.