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

 It is currently 24 Aug 2016, 10:26

### 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

# Events & Promotions

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

# If n is a positive integer, is n3 n divisible by 4? 1. n =

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

### Hide Tags

SVP
Joined: 04 May 2006
Posts: 1926
Schools: CBS, Kellogg
Followers: 21

Kudos [?]: 852 [1] , given: 1

If n is a positive integer, is n3 n divisible by 4? 1. n = [#permalink]

### Show Tags

24 Feb 2008, 18:59
1
This post received
KUDOS
1
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

63% (02:05) correct 37% (01:34) wrong based on 93 sessions

### HideShow timer Statistics

147. If n is a positive integer, is n3 – n divisible by 4?

1. n = 2k + 1
2. n2 + n is divisible by 6
[Reveal] Spoiler: OA

_________________
SVP
Joined: 28 Dec 2005
Posts: 1575
Followers: 3

Kudos [?]: 129 [0], given: 2

Re: If n is a positive integer, is n3 n divisible by 4? 1. n = [#permalink]

### Show Tags

24 Feb 2008, 20:03
Taking too long on this one ... have it down to C or E
Current Student
Joined: 28 Dec 2004
Posts: 3385
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 14

Kudos [?]: 257 [1] , given: 2

Re: If n is a positive integer, is n3 n divisible by 4? 1. n = [#permalink]

### Show Tags

24 Feb 2008, 21:30
1
This post received
KUDOS
i get A for this one... a lil rusty..

here is how

stem asks (n-1)*n*(n+1) is divisible by 4?

well basically we know the above is divisible by 3..

1) n=2K+1 basically says n=odd
if n is odd, yes the above is divisible by 4..sufficient

2) n(n+1)=6
basically n can be 2 or 3..or n can be 3 or 4.. if n=2 then the stem is not divisible by 4..if n=3 it is divisible by 4..insuff..

A it is..
Senior Manager
Joined: 15 Aug 2007
Posts: 252
Schools: Chicago Booth
Followers: 1

Kudos [?]: 61 [0], given: 0

Re: If n is a positive integer, is n3 n divisible by 4? 1. n = [#permalink]

### Show Tags

24 Feb 2008, 21:33
Is the question complete? please use "^" for exponents, if any.

Assuming n3-n = n^3 - n

1. suff. whether n = 2^k + 1 or n = 2*k + 1, n is always odd.
2. insuff. assuming the equation is n^2 + n, if n is divisible by 6 it doesn't meant n is divisible by 4.

So A.
SVP
Joined: 04 May 2006
Posts: 1926
Schools: CBS, Kellogg
Followers: 21

Kudos [?]: 852 [0], given: 1

Re: If n is a positive integer, is n3 n divisible by 4? 1. n = [#permalink]

### Show Tags

24 Feb 2008, 23:42
sreehari wrote:
Is the question complete? please use "^" for exponents, if any.

Assuming n3-n = n^3 - n

1. suff. whether n = 2^k + 1 or n = 2*k + 1, n is always odd.
2. insuff. assuming the equation is n^2 + n, if n is divisible by 6 it doesn't meant n is divisible by 4.

So A.

You are right!

And OA is A, thank you!
_________________
Intern
Joined: 23 Jun 2010
Posts: 37
Followers: 0

Kudos [?]: 21 [0], given: 5

Re: If n is a positive integer, is n3 n divisible by 4? 1. n = [#permalink]

### Show Tags

26 Feb 2011, 00:25
1
This post was
BOOKMARKED
FN wrote:
i get A for this one... a lil rusty..

here is how

stem asks (n-1)*n*(n+1) is divisible by 4?

well basically we know the above is divisible by 3..

1) n=2K+1 basically says n=odd
if n is odd, yes the above is divisible by 4..sufficient

2) n(n+1)=6
basically n can be 2 or 3..or n can be 3 or 4.. if n=2 then the stem is not divisible by 4..if n=3 it is divisible by 4..insuff..

A it is..

I like the approach you have taken here to translate n^3 - n to (n-1)*n*(n+1). It makes A a clear choice. I went a longer route of seeing whether n(n^2 - 1) is divisible by 4 i.e. whether either n on its own or n^2 - 1 was divisible by 4. It took WAY longer than 2 mins to reach the conclusion. Simplifying n*(n^2 -1) one step further makes total sense.
Kudos from me!
_________________

-DK
---------------------------------------------------------
If you like what you read then give a Kudos!
Diagnostic Test: 620
The past is a guidepost, not a hitching post.
---------------------------------------------------------

Math Expert
Joined: 02 Sep 2009
Posts: 34420
Followers: 6248

Kudos [?]: 79391 [0], given: 10016

Re: If n is a positive integer, is n3 n divisible by 4? 1. n = [#permalink]

### Show Tags

26 Feb 2011, 03:51
This question is discussed here: og-ds-170arithmetic-109941.html
_________________
Re: If n is a positive integer, is n3 n divisible by 4? 1. n =   [#permalink] 26 Feb 2011, 03:51
Similar topics Replies Last post
Similar
Topics:
6 If n is a positive integer, is n^3 – n divisible by 4 ? 8 12 Mar 2012, 02:52
If n is a positive integer, is n^3 - n divisible by 4? (1) n 2 18 Jun 2011, 22:09
17 If n is a positive integer, is n^3 n divisible by 4 ? 12 23 Feb 2011, 22:25
2 If n is a positive integer, is n^3-n divisible by 4? 1. 5 03 Feb 2010, 18:18
5 If n is a positive integer, is n^3 – n divisible by 4? 9 18 Aug 2009, 08:53
Display posts from previous: Sort by

# If n is a positive integer, is n3 n divisible by 4? 1. n =

 post reply Question banks Downloads My Bookmarks Reviews Important topics

 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®.