Remainder Problem

This topic has expert replies
Source: — Data Sufficiency |

Junior | Next Rank: 30 Posts
Posts: 11
Joined: Tue Sep 15, 2009 6:01 am
Location: Lagos

by Onigbogi Tosin » Mon Sep 28, 2009 11:52 pm
Please, I really need solution to this problem. Thanks

Master | Next Rank: 500 Posts
Posts: 182
Joined: Sun Aug 02, 2009 7:19 pm
Thanked: 18 times
GMAT Score:680

by sanjana » Tue Sep 29, 2009 2:59 am
IMO - A

If you see powers of 3 when divided by 10 yeild remainders in a pattern

3^1 - remainder 3
3^2 - remainder 9
3^3 - remainder 7
3^4 - remainder 1
3^5 - remainder 3
and the pattern repeats as 3,7,9,1,3,7,9,1 etc

therefore 4n+1 powers yeild remainder 3
4n+2 powers yeild remainder 9
etc

now from A) n=2

Therefore we want to find (3^10)/10 = 7

Therefore A is sufficient

B) gives the value of M which is insufficient as m doesnt come into the picture here.

Hope this helps.

Let me know if the OA ia A.

Senior | Next Rank: 100 Posts
Posts: 43
Joined: Tue Mar 31, 2009 9:54 am
Thanked: 2 times

by glorydefined » Tue Sep 29, 2009 4:42 am
IMO :A , but this is defenitely not a GMAT question...

Legendary Member
Posts: 1578
Joined: Sun Dec 28, 2008 1:49 am
Thanked: 82 times
Followed by:9 members
GMAT Score:720

Re: Remainder Problem

by maihuna » Tue Sep 29, 2009 4:53 am
Onigbogi Tosin wrote:If n and m are positive integers, what is the remainder when 3^(4n+2) is divided by 10?
(1) n = 2
(2) m = 1
Where is the m in question stem, check in case you have typed it correctly....
Charged up again to beat the beast :)

Junior | Next Rank: 30 Posts
Posts: 11
Joined: Tue Sep 15, 2009 6:01 am
Location: Lagos

by Onigbogi Tosin » Wed Sep 30, 2009 7:18 am
sanjana wrote:IMO - A

If you see powers of 3 when divided by 10 yeild remainders in a pattern

3^1 - remainder 3
3^2 - remainder 9
3^3 - remainder 7
3^4 - remainder 1
3^5 - remainder 3
and the pattern repeats as 3,7,9,1,3,7,9,1 etc

therefore 4n+1 powers yeild remainder 3
4n+2 powers yeild remainder 9
etc

now from A) n=2

Therefore we want to find (3^10)/10 = 7

Therefore A is sufficient

B) gives the value of M which is insufficient as m doesnt come into the picture here.

Hope this helps.

Let me know if the OA ia A.
I actually got the question from the GMAT PREP, and the answer there is B.

Junior | Next Rank: 30 Posts
Posts: 11
Joined: Tue Sep 15, 2009 6:01 am
Location: Lagos

by Onigbogi Tosin » Wed Sep 30, 2009 7:42 am
sanjana wrote:IMO - A

If you see powers of 3 when divided by 10 yeild remainders in a pattern

3^1 - remainder 3
3^2 - remainder 9
3^3 - remainder 7
3^4 - remainder 1
3^5 - remainder 3
and the pattern repeats as 3,7,9,1,3,7,9,1 etc

therefore 4n+1 powers yeild remainder 3
4n+2 powers yeild remainder 9
etc

now from A) n=2

Therefore we want to find (3^10)/10 = 7

Therefore A is sufficient

B) gives the value of M which is insufficient as m doesnt come into the picture here.

Hope this helps.

Let me know if the OA ia A.
I actually got the question from the GMAT PREP, and the answer there is B.

Junior | Next Rank: 30 Posts
Posts: 11
Joined: Tue Sep 15, 2009 6:01 am
Location: Lagos

Re: Remainder Problem

by Onigbogi Tosin » Wed Sep 30, 2009 7:49 am
maihuna wrote:
Onigbogi Tosin wrote:If n and m are positive integers, what is the remainder when 3^(4n+2) is divided by 10?
(1) n = 2
(2) m = 1
Where is the m in question stem, check in case you have typed it correctly....
I got the question from the Gmat Prep, and the answer there is B

Junior | Next Rank: 30 Posts
Posts: 11
Joined: Tue Sep 15, 2009 6:01 am
Location: Lagos

by Onigbogi Tosin » Wed Sep 30, 2009 7:56 am
glorydefined wrote:IMO :A , but this is defenitely not a GMAT question...
It is definitely a GMAT PREP question and the answer there is B

User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

Re: Remainder Problem

by Stuart@KaplanGMAT » Wed Sep 30, 2009 12:14 pm
Onigbogi Tosin wrote:If n and m are positive integers, what is the remainder when 3^(4n+2) is divided by 10?
(1) n = 2
(2) m = 1
How can the answer possibly be B when there's no "m" in the question? You definitely missed part of the question.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course