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

It is currently 27 Aug 2014, 17:05

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

DS - divided by 10

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
avatar
Joined: 27 Dec 2009
Posts: 172
Followers: 2

Kudos [?]: 23 [0], given: 3

GMAT Tests User
DS - divided by 10 [#permalink] New post 17 Jan 2010, 08:46
If x is a positive integer, is the remainder 0 when 3^x + 1 is divided by 10?
(1) x = 4n + 2, where n is a positive integer.
(2) x > 4

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient

What will be the correct answer ?
1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2009
Posts: 290
Location: India
Concentration: General Management
Followers: 2

Kudos [?]: 93 [1] , given: 5

GMAT Tests User
Re: DS - divided by 10 [#permalink] New post 17 Jan 2010, 22:59
1
This post received
KUDOS
msand wrote:
If x is a positive integer, is the remainder 0 when 3^x + 1 is divided by 10?
(1) x = 4n + 2, where n is a positive integer.
(2) x > 4

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient

What will be the correct answer ?


will go with A
1. 3^x has a cyclicity of 4 ie
3^1 = 3
3^2 =9
3^3 = 27[last digit 7]
3^4 = 81[last digit 1]
3^5 =243[last digit 3]

so 3^(4n+2) will be 3^6/3^10/3^14 wherein last digit will always be 9 and so 3^(4n+2) + 1 will have last digit as 0 which is divisible by 10. hence suff

stmnt 2: x>4 let x = 5 then 3^5 = 243
243 +1 = 244 not divisible by 10

let x=6 3^3 = 729
729 + 1 = 730. divisible by 10
hence not suff
CEO
CEO
User avatar
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2793
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Followers: 178

Kudos [?]: 926 [0], given: 235

GMAT Tests User Reviews Badge
Re: DS - divided by 10 [#permalink] New post 18 Jan 2010, 09:12
Yes it should be A as explained above.
OA pls.
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned :)

Jo Bole So Nihaal , Sat Shri Akaal

:thanks Support GMAT Club by putting a GMAT Club badge on your blog/Facebook :thanks

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Gmat test review :
670-to-710-a-long-journey-without-destination-still-happy-141642.html

Re: DS - divided by 10   [#permalink] 18 Jan 2010, 09:12
    Similar topics Author Replies Last post
Similar
Topics:
DS question OG 10 pranrasvij 1 17 Jun 2010, 11:27
Experts publish their posts in the topic m11#10 - DS ykaiim 5 11 Jun 2010, 05:57
DS: t divided by 7 judokan 23 05 Sep 2008, 02:57
16 Experts publish their posts in the topic M10: Q10 - DS balboa 17 22 Aug 2008, 14:34
ds og 10 # 11 mand-y 6 27 Nov 2005, 13:14
Display posts from previous: Sort by

DS - divided by 10

  Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: Bunuel, WoundedTiger



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®.