Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 27 May 2017, 17:33

### 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

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 S is a series of numbers of the form X, XX, XXX, XXXX,

Author Message
Manager
Joined: 01 Nov 2007
Posts: 144
Followers: 2

Kudos [?]: 364 [17] , given: 0

If S is a series of numbers of the form X, XX, XXX, XXXX, [#permalink]

### Show Tags

13 Feb 2008, 16:46
17
KUDOS
2
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If S is a series of numbers of the form X, XX, XXX, XXXX, XXXXX, ..., where X is a non-zero digit, is every number in this series a multiple of the same prime number P?

(1) P is an odd number such that P < X

(2) X is a multiple of P
Senior Manager
Joined: 26 Jan 2008
Posts: 263
Followers: 4

Kudos [?]: 109 [1] , given: 16

### Show Tags

13 Feb 2008, 18:48
1
KUDOS
JCLEONES wrote:
If S is a series of numbers of the form X, XX, XXX, XXXX, XXXXX, ..., where X is a non-zero digit, is every number in this series a multiple of the same prime number P?

(1) P is an odd number such that P < X

(2) X is a multiple of P

(1) P is an odd single-digit prime number. It can be either 3, 5 or 7. If every number of series S were to be a multiple of P, then X is divisible by P. Also, X > P. So if P = 3, X can be either 6 or 9. If P = 5 or P = 7, no value of X suffices. Hence the series can be {6, 66, 666...} or {9, 99, 999...} and each term is divisible by 3. Sufficient.

(2) Sufficient. Try plugging in X=2, P=2 or X=6, P=3.
_________________
CEO
Joined: 17 Nov 2007
Posts: 3586
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 575

Kudos [?]: 3982 [2] , given: 360

### Show Tags

14 Feb 2008, 02:58
2
KUDOS
Expert's post
B

If S is a series of numbers of the form X, XX, XXX, XXXX, XXXXX, ..., where X is a non-zero digit, is every number in this series a multiple of the same prime number P?

(1) P is an odd number such that P < X
P can be 3,5,7
for example, P=3:
in series 6,66,666,6666... every number is divisible by 3
in series 7,77,777,7777... not every number is divisible by 3
insuff.

(2) X is a multiple of P: X=k*P
XXXX...XXX=X*(111...111)=P*(k*111...111) is divisible by P
suff.
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Senior Manager
Joined: 26 Jan 2008
Posts: 263
Followers: 4

Kudos [?]: 109 [0], given: 16

### Show Tags

14 Feb 2008, 10:21
walker wrote:
B

If S is a series of numbers of the form X, XX, XXX, XXXX, XXXXX, ..., where X is a non-zero digit, is every number in this series a multiple of the same prime number P?

(1) P is an odd number such that P < X
P can be 3,5,7
for example, P=3:
in series 6,66,666,6666... every number is divisible by 3
in series 7,77,777,7777... not every number is divisible by 3
insuff.

(2) X is a multiple of P: X=k*P
XXXX...XXX=X*(111...111)=P*(k*111...111) is divisible by P
suff.

+1. Made an assumption I shouldn't have!
_________________
Re: DS - Primes   [#permalink] 14 Feb 2008, 10:21
Display posts from previous: Sort by