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

It is currently 29 May 2016, 20:14
GMAT Club Tests

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 quick litmus test to see whether an integer is

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
CEO
CEO
User avatar
Joined: 21 Jan 2007
Posts: 2756
Location: New York City
Followers: 9

Kudos [?]: 603 [0], given: 4

What is the quick litmus test to see whether an integer is [#permalink]

Show Tags

New post 26 Oct 2007, 09:48
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

What is the quick litmus test to see whether an integer is divisible by 7
VP
VP
avatar
Joined: 10 Jun 2007
Posts: 1459
Followers: 6

Kudos [?]: 200 [0], given: 0

Re: Divisibility Rule [#permalink]

Show Tags

New post 26 Oct 2007, 12:37
bmwhype2 wrote:
What is the quick litmus test to see whether an integer is divisible by 7


No rules that I know of.
Prime factorization? Or just divide by 7, shouldn't take that long...
CEO
CEO
User avatar
Joined: 21 Jan 2007
Posts: 2756
Location: New York City
Followers: 9

Kudos [?]: 603 [0], given: 4

Re: Divisibility Rule [#permalink]

Show Tags

New post 26 Oct 2007, 12:39
bkk145 wrote:
bmwhype2 wrote:
What is the quick litmus test to see whether an integer is divisible by 7


No rules that I know of.
Prime factorization? Or just divide by 7, shouldn't take that long...


I came across several questions that asked this concept.


is 342234234123 divisible by 7? lol
VP
VP
User avatar
Joined: 08 Jun 2005
Posts: 1146
Followers: 6

Kudos [?]: 163 [0], given: 0

Re: Divisibility Rule [#permalink]

Show Tags

New post 26 Oct 2007, 12:50
bmwhype2 wrote:
bkk145 wrote:
bmwhype2 wrote:
What is the quick litmus test to see whether an integer is divisible by 7


No rules that I know of.
Prime factorization? Or just divide by 7, shouldn't take that long...


I came across several questions that asked this concept.


is 342,234,234,123 divisible by 7? lol


I use approximation

since ---> 7*4 = 28 ---> then:

342,234,234,123 - 280,000,000,000 = 62,234,234,123

7*8 = 56

62,234,234,123 - 56,000,000,000 = 6,234,234,123

6,234,234,123 - 5,600,000,000 = 634,234,123

634,234,123 - 560,000,000 = 74,234,123

7*10 = 70

74,234,123 - 70,000,000 = 4,234,123

7*6 = 42

4,234,123 - 4,200,000 = 34,123

34,123 - 28,000 = 6,123

6,123 - 5,600 = 523

523 - 490 = 33

this number dosen't divide by 7 !

:)
VP
VP
avatar
Joined: 10 Jun 2007
Posts: 1459
Followers: 6

Kudos [?]: 200 [0], given: 0

Re: Divisibility Rule [#permalink]

Show Tags

New post 26 Oct 2007, 13:19
bmwhype2 wrote:
bkk145 wrote:
bmwhype2 wrote:
What is the quick litmus test to see whether an integer is divisible by 7


No rules that I know of.
Prime factorization? Or just divide by 7, shouldn't take that long...


I came across several questions that asked this concept.


is 342234234123 divisible by 7? lol


I would just divide that number by 7. Should take about 20 seconds max.
Do you have an actual problem?
Re: Divisibility Rule   [#permalink] 26 Oct 2007, 13:19
Display posts from previous: Sort by

What is the quick litmus test to see whether an integer is

  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 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®.