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

It is currently 18 Apr 2014, 07:55

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

This one is from a Kaplan test I took : What is the

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
Joined: 20 Mar 2007
Posts: 62
Followers: 1

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

This one is from a Kaplan test I took : What is the [#permalink] New post 12 Aug 2007, 19:29
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
This one is from a Kaplan test I took :

What is the result of adding the units digit of 2002^2002 and 7007^7007?
A) 1
B) 4
C) 5
D) 7
E) 9


OA is D .Can someone explain how to do this.
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesManhattan GMAT Discount Codes
Director
Director
Joined: 11 Jun 2007
Posts: 933
Followers: 1

Kudos [?]: 32 [0], given: 0

GMAT Tests User
Re: PS question - number properties [#permalink] New post 12 Aug 2007, 19:41
Kiski wrote:
This one is from a Kaplan test I took :

What is the result of adding the units digit of 2002^2002 and 7007^7007?
A) 1
B) 4
C) 5
D) 7
E) 9


OA is D .Can someone explain how to do this.


Since we are only looking at the units digit:
2002^2002
2 * 2 = 4
we know 2002^2002 ends with 4

7007^7007
7^1 = 7
7^2 = 49
7^3 = 343
7^4 = 343*7 ends in 1
7^5 = 1 * 7 = ends with 7 <-- here is where the sequence repeats
7^6 = 7 * 7 = ends with 9
7^7 = 9 * 7 = ends with 3
we know 7007^7007 ends with 3

thus adding the two unit digits: 4+3 = 7 (D)
Director
Director
User avatar
Joined: 03 May 2007
Posts: 899
Schools: University of Chicago, Wharton School
Followers: 5

Kudos [?]: 35 [0], given: 6

GMAT Tests User
Re: PS question - number properties [#permalink] New post 12 Aug 2007, 20:22
Kiski wrote:
This one is from a Kaplan test I took :

What is the result of adding the units digit of 2002^2002 and 7007^7007?
A) 1
B) 4
C) 5
D) 7
E) 9


OA is D .Can someone explain how to do this.


2^1=2
2^2=4
2^3=8
2^4=16

2^5=32
2^6=64
2^7=128
2^8=256

see the pattren. in every 4 powers, the pattren repeats.
so 2002^2002 has 4 in unit digit.


similarly:
7^1=7
7^2=49
7^3=343
7^4=2401
7^4=16807

now here to the repeats after every 4 powers and 7007^7007 has 3 in unit digit.

therfore the sum is 7.
Intern
Intern
Joined: 10 Aug 2007
Posts: 30
Followers: 0

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

 [#permalink] New post 12 Aug 2007, 21:52
Just thought I should mention/ask: Once you have the pattern, you divide the exponent by the number in the sequence (four for both 2002 and 7007 in this case) and then your remainder determines what the actual digit is...correct?

So, in this case:

2
4
8
6
-------> cycle is 4, so 2002 / 4 = 500 r2, so the digit is the second number in the sequence: 4

7
9
3
1
-------> cycle is also 4, so 7007 / 4 = 1751 r3, so the digit is the third number in the sequence: 3
  [#permalink] 12 Aug 2007, 21:52
    Similar topics Author Replies Last post
Similar
Topics:
New posts Took Kaplan FLT, what score can i expect shantanu4678 7 14 Nov 2004, 09:33
New posts From a Kaplan Practice Test: What is the units digit of peachtree 6 03 Jul 2006, 07:33
New posts I just took my first test on GMATPrep, this one caught me seofah 3 24 Apr 2007, 12:44
This topic is locked, you cannot edit posts or make further replies. New Here is one that came in a test I tooked last week: as aljcarranza 0 08 Dec 2010, 15:48
New posts took one practice test from gmat prep anshulece11 1 15 Aug 2012, 13:10
Display posts from previous: Sort by

This one is from a Kaplan test I took : What is the

  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®.