It is currently 22 Feb 2018, 12:31

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is the sum of ALL the factors of 49?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 43867
What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 16 Nov 2016, 03:53
Expert's post
3
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

77% (00:26) correct 23% (00:14) wrong based on 139 sessions

HideShow timer Statistics

Senior Manager
Senior Manager
User avatar
P
Status: Preparing for GMAT
Joined: 25 Nov 2015
Posts: 485
Location: India
GPA: 3.64
GMAT ToolKit User Premium Member Reviews Badge
Re: What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 16 Nov 2016, 05:06
When an integer n can be expressed as \(a^p*b^q*c^r\), where a,b,c are prime factors of n and p,q,r are their powers,
the sum of the factors of n can be expressed as \(\frac{(a^p+1-1)*(b^q+1-1)*(c^r+1-1)}{(a-1)*(b-1)*(c-1)}\)

49=\(7^2\)
Applying the formula, \(\frac{(7^2+1-1)}{(7-1)=(7^3-1)/6}\) = 57
So, answer E.
_________________

Please give kudos, if you like my post

When the going gets tough, the tough gets going...

Senior Manager
Senior Manager
avatar
Joined: 06 Jun 2016
Posts: 263
Location: India
Concentration: Operations, Strategy
Schools: ISB '18 (D)
GMAT 1: 600 Q49 V23
GMAT 2: 680 Q49 V34
GPA: 3.9
Re: What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 16 Nov 2016, 05:42
Bunuel wrote:
What is the sum of ALL the factors of 49?

A. 7
B. 8
C. 50
D. 51
E. 57


Factors of 49 = 1, 7, 49
Sum= 57
E
Board of Directors
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3326
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 16 Nov 2016, 07:31
Bunuel wrote:
What is the sum of ALL the factors of 49?

A. 7
B. 8
C. 50
D. 51
E. 57


Factors of 49 are 1 , 7 & 49

Sum of all the factors is 1 + 7 + 49 = 57

Hence, answer will be (E) 57

_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Board of Directors
User avatar
P
Joined: 17 Jul 2014
Posts: 2732
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge
Re: What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 16 Nov 2016, 07:42
Bunuel wrote:
What is the sum of ALL the factors of 49?

A. 7
B. 8
C. 50
D. 51
E. 57


what are the factors of 49?
1, 7, 49

1+7+49 = 57
answer must be E.
Intern
Intern
avatar
Joined: 14 Oct 2013
Posts: 15
GMAT ToolKit User
Re: What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 16 Nov 2016, 07:49
Factors of 49 --> 1, 7 and 49

Sum of factors = 1 + 7 + 49 = 57

Option E
Manager
Manager
User avatar
B
Joined: 19 Jul 2017
Posts: 85
Location: India
Concentration: General Management, Strategy
GPA: 3.5
Re: What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 27 Aug 2017, 04:07
Applying the formula here (7^(2+1) -1)/(7-1) = (7^3 -1)/6

= 342/6 =57
1 KUDOS received
Manager
Manager
User avatar
G
Joined: 30 May 2012
Posts: 217
Location: United States (TX)
Concentration: Finance, Marketing
GPA: 3.3
WE: Information Technology (Consulting)
Premium Member
What is the sum of ALL the factors of 49? [#permalink]

Show Tags

New post 31 Aug 2017, 04:40
1
This post received
KUDOS
Steps:

1. Find the prime factors to the number in question

2. Sub in the formula below

\(\frac{[a^{(n+1)} -1][b^{(n+1)} -1][c^{(n+1)} -1]...}{[a-1][b-1][c-1]...}\)

So, referring back to the question:

1. Find the prime factors of 49, which is \(7^2\)

2. Subbing in the formula, we get:

=\(\frac{[7^{(2+1)} -1]}{[7-1]}\)

= \(\frac{[343-1]}{6}\) (we get 343 because \(7^3\)= 343)

= 342/6

= 57

Now, if there are more prime factors to a given number, we could substitute each prime factor in place of a or b or c and so on in the formula above.

Hope that helps!
What is the sum of ALL the factors of 49?   [#permalink] 31 Aug 2017, 04:40
Display posts from previous: Sort by

What is the sum of ALL the factors of 49?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


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

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®.