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

It is currently 18 Sep 2014, 19:58

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

If 243^x*463^y = n, where x and y are positive integers, wha

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
User avatar
Joined: 06 Jul 2006
Posts: 295
Location: SFO Bay Area
Schools: Berkeley Haas
Followers: 2

Kudos [?]: 31 [0], given: 0

GMAT Tests User
If 243^x*463^y = n, where x and y are positive integers, wha [#permalink] New post 29 Mar 2008, 20:11
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

47% (01:37) correct 53% (01:48) wrong based on 19 sessions
If (243)^x(463)^y = n, where x and y are positive integers, what is the units digit of n?

(1) x + y = 7

(2) x = 4

OPEN DISCUSSION OF THIS QUESTION IS HERE: if-243-x-463-y-n-where-x-and-y-are-positive-integers-102054.html
[Reveal] Spoiler: OA

Last edited by Bunuel on 12 Jul 2013, 00:45, edited 2 times in total.
Edited the question and added the OA
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesVeritas Prep GMAT Discount Codes
Manager
Manager
avatar
Joined: 27 Mar 2008
Posts: 53
Followers: 1

Kudos [?]: 6 [0], given: 0

Re: PS: what is the units digit of n ? [#permalink] New post 29 Mar 2008, 20:17
[Edited]

The question was entered as (243)x(463)y initially. Please ignore this post.

Last edited by purefocus428 on 17 Apr 2008, 17:51, edited 1 time in total.
Senior Manager
Senior Manager
User avatar
Joined: 06 Jul 2006
Posts: 295
Location: SFO Bay Area
Schools: Berkeley Haas
Followers: 2

Kudos [?]: 31 [0], given: 0

GMAT Tests User
Re: PS: what is the units digit of n ? [#permalink] New post 29 Mar 2008, 20:26
suntaurian wrote:
Came across this interesting question. Thought I will share with you guys....

If (243)^x(463)^y = n, where x and y are positive integers, what is the units digit of n?

(1) x + y = 7

(2) x = 4


Edited the question to properly indicate that its 243^x and 463^y.. Sorry about that...
Senior Manager
Senior Manager
User avatar
Joined: 06 Jul 2006
Posts: 295
Location: SFO Bay Area
Schools: Berkeley Haas
Followers: 2

Kudos [?]: 31 [0], given: 0

GMAT Tests User
Re: PS: what is the units digit of n ? [#permalink] New post 29 Mar 2008, 20:34
purefocus428 wrote:
(243)x(463)y has the same units digit as 3x3y or 9xy.

(1) x + y = 7
x and y could be (0,7) or (2,5) which would give different answers
INSUFF

(2) x = 4
No way of knowing what y is,
INSUFF

(1 and 2) Since x+y = 7, the fact that x = 4 means that y is 3.
9(4)(3) gives a units digit of 8

(C)


Keep trying...Will post the OA after few others have tried as well...
Manager
Manager
avatar
Joined: 20 Aug 2007
Posts: 66
Followers: 1

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

Re: PS: what is the units digit of n ? [#permalink] New post 29 Mar 2008, 21:47
suntaurian wrote:
Came across this interesting question. Thought I will share with you guys....

If (243)^x(463)^y = n, where x and y are positive integers, what is the units digit of n?

(1) x + y = 7

(2) x = 4


looking at unit digit
3^1 = 3
3^2 = 9
3^3 = 7
3^4 = 1
3^5 = 3
3^6 = 9

1) sufficient - any combinations of x and y will result in unit digit of 7
i.e. x=1 y=6; unit digit = 3*9=7
x=2, y=5; unit digit = 9*3=7
x=3, y=4; unit digit = 7*1=7
also vice versa

2) not sufficient, we need to know y in this case

I'd go with A
CEO
CEO
User avatar
Joined: 29 Aug 2007
Posts: 2501
Followers: 53

Kudos [?]: 506 [0], given: 19

GMAT Tests User
Re: PS: what is the units digit of n ? [#permalink] New post 29 Mar 2008, 22:11
suntaurian wrote:
suntaurian wrote:
Came across this interesting question. Thought I will share with you guys....

If (243)^x(463)^y = n, where x and y are positive integers, what is the units digit of n?

(1) x + y = 7

(2) x = 4


Edited the question to properly indicate that its 243^x and 463^y.. Sorry about that...


A is suff since the last digit of either of the number is 3.
_________________

Verbal: new-to-the-verbal-forum-please-read-this-first-77546.html
Math: new-to-the-math-forum-please-read-this-first-77764.html
Gmat: everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

Manager
Manager
avatar
Joined: 27 Mar 2008
Posts: 53
Followers: 1

Kudos [?]: 6 [0], given: 0

Re: PS: what is the units digit of n ? [#permalink] New post 29 Mar 2008, 22:32
Ah, well that changes the question now that I know they are exponents :P

I would still do same approach where I believe that only the units digits make a difference.

(243)^x(463)^y has the same units digit as (3^x)(3^y) or 3^(x+y)

Since Statement 1 gives the value of x+y as seven, the answer is (A) since statement 2 doesn't help by itself.
Manager
Manager
avatar
Joined: 27 Mar 2008
Posts: 53
Followers: 1

Kudos [?]: 6 [0], given: 0

Re: PS: what is the units digit of n ? [#permalink] New post 29 Mar 2008, 22:33
suntaurian wrote:
purefocus428 wrote:
(243)x(463)y has the same units digit as 3x3y or 9xy.

(1) x + y = 7
x and y could be (0,7) or (2,5) which would give different answers
INSUFF

(2) x = 4
No way of knowing what y is,
INSUFF

(1 and 2) Since x+y = 7, the fact that x = 4 means that y is 3.
9(4)(3) gives a units digit of 8

(C)


Keep trying...Will post the OA after few others have tried as well...


Please ignore this post. Looks like I answered it at the same time the post was being corrected.
Current Student
avatar
Joined: 28 Dec 2004
Posts: 3404
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 159 [0], given: 2

GMAT Tests User
Re: PS: what is the units digit of n ? [#permalink] New post 17 Apr 2008, 17:22
short way to do this is to realize the unit digit of each number is 3..

therefore the unit digit of N= 3^(x+y)=3^7=7

A it is..
Re: PS: what is the units digit of n ?   [#permalink] 17 Apr 2008, 17:22
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic If 243^x*463^y = n, where x and y are positive integers, wha mattapraveen 4 05 Nov 2010, 03:05
7 Experts publish their posts in the topic If 243^x*463^y = n, where x and y are positive integers anilnandyala 8 02 Oct 2010, 03:44
4 Experts publish their posts in the topic If (243)^x(463)^y = n, where x and y are positive integers, rohitgoel15 8 07 Apr 2010, 22:37
If (243)x(463)y = n, where x and y are positive integers, ldpedroso 11 27 May 2008, 18:45
If (243)^x * (463)^y = n, where x and y are positive jimjohn 5 30 Oct 2007, 10:54
Display posts from previous: Sort by

If 243^x*463^y = n, where x and y are positive integers, wha

  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®.