If a and b are the digits of the two-digit number X, what is : DS Archive
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 22 Jan 2017, 07:24

### 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 a and b are the digits of the two-digit number X, what is

Author Message
Intern
Joined: 01 Dec 2007
Posts: 31
Followers: 1

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

If a and b are the digits of the two-digit number X, what is [#permalink]

### Show Tags

01 Dec 2007, 20:56
00:00

Difficulty:

(N/A)

Question Stats:

100% (01:31) correct 0% (00:00) wrong based on 25 sessions

### HideShow timer Statistics

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

If a and b are the digits of the two-digit number X, what is the remainder when X is divided by 9?

(1) a + b = 11

(2) X + 7 is divisible by 9

What's the fastests way to solve this problem?
CEO
Joined: 17 Nov 2007
Posts: 3589
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 549

Kudos [?]: 3562 [0], given: 360

### Show Tags

01 Dec 2007, 21:20
D.

1. X(mod9)=(a+b)mod9=11(mod9)=2(mod9)
1. (X+7)mod9=0 ==> X+7=9n ==> X=9n-7 or X=9(n-1)+2 X(mod9)=2(mod9)
CEO
Joined: 17 Nov 2007
Posts: 3589
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 549

Kudos [?]: 3562 [0], given: 360

### Show Tags

01 Dec 2007, 21:33
applecrisp wrote:
What's mod9?

a(mod b)- reminder (a divided by b)

for example,
56(mod 11)=1(mod 11) ==> 56=11n+1
SVP
Joined: 05 Jul 2006
Posts: 1743
Followers: 6

Kudos [?]: 317 [0], given: 49

### Show Tags

02 Dec 2007, 02:38
applecrisp wrote:
If a and b are the digits of the two-digit number X, what is the remainder when X is divided by 9?

(1) a + b = 11

(2) X + 7 is divisible by 9

What's the fastests way to solve this problem?

FROM 1

A,B <10 THUS A,B = (9,2)OR (7,4) OR (5,6) OR (2.9) 0R (4,7)..ETC.......SUFF ALWAYS REMINDER WILL BE 2.

X+7 = 9K IE: X = 9K-7 , 9K - 7 / 9 RMINDER IS ALWAYS 2..SUFF

Re: DS Remainder   [#permalink] 02 Dec 2007, 02:38
Display posts from previous: Sort by