It is currently 11 Dec 2017, 00:47

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If the tens digit x and the units digit y of a positive integer n are

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Intern
Intern
avatar
Joined: 03 Dec 2010
Posts: 43

Kudos [?]: 47 [0], given: 7

If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 15:46
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

62% (01:07) correct 38% (01:01) wrong based on 90 sessions

HideShow timer Statistics

If the tens digit x and the units digit y of a positive integer n are reversed, the resulting integer is 9 more than n. What is y in terms of x ?

(A) 10 - x
(B) 9 - x
(C) x + 9
(D) x - 1
(E) x + 1
[Reveal] Spoiler: OA

Kudos [?]: 47 [0], given: 7

Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 1949

Kudos [?]: 2130 [0], given: 376

Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 15:59
1
This post was
BOOKMARKED
Acer86 wrote:
If the tens digit x and the units digit y of a positive integer n are reversed, the resulting integer is 9 more than n. What is y in terms of x ?
(A) 10 - x
(B) 9 - x
(C) x + 9
(D) x - 1
(E) x + 1


Original Digits=xy i.e. Number=10x+y

After reversing the digits:
Digits=yx i.e. Number=10y+x

10y+x is 9 more than 10x+y

10x+y+9=10y+x
10x-x+9=10y-y
9x+9=9y
x+1=y
OR
y=x+1

Ans: "E"
_________________

~fluke

GMAT Club Premium Membership - big benefits and savings

Kudos [?]: 2130 [0], given: 376

Intern
Intern
avatar
Joined: 03 Dec 2010
Posts: 43

Kudos [?]: 47 [0], given: 7

Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 16:05
fluke wrote:
Acer86 wrote:
If the tens digit x and the units digit y of a positive integer n are reversed, the resulting integer is 9 more than n. What is y in terms of x ?
(A) 10 - x
(B) 9 - x
(C) x + 9
(D) x - 1
(E) x + 1


Original Digits=xy i.e. Number=10x+y

After reversing the digits:
Digits=yx i.e. Number=10y+x

10y+x is 9 more than 10x+y

10x+y+9=10y+x
10x-x+9=10y-y
9x+9=9y
x+1=y
OR
y=x+1

Ans: "E"




hey can u explain the concept behind this. As in how do the digits become 10y+x from yx when switched over. Thanks.

Kudos [?]: 47 [0], given: 7

Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 1949

Kudos [?]: 2130 [0], given: 376

Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 16:09
Acer86 wrote:
hey can u explain the concept behind this. As in how do the digits become 10y+x from yx when switched over. Thanks.


It is a way to represent a number when digits are known:

38=3*10+8
4567=4*1000+5*100+6*10+7

Thus, every digit will be multiplied by its place value.

xy
Here x is at Ten's place and y is at units place:
Number = 10*x+y

yx
Here y is at Ten's place and x is at units place:
Number = 10*y+x

Like:
89
Number = 8*10+9

98
Number = 9*10+8
_________________

~fluke

GMAT Club Premium Membership - big benefits and savings

Kudos [?]: 2130 [0], given: 376

Intern
Intern
avatar
Joined: 03 Dec 2010
Posts: 43

Kudos [?]: 47 [0], given: 7

Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 16:17
Thank you so much :)

Kudos [?]: 47 [0], given: 7

Director
Director
avatar
Joined: 01 Feb 2011
Posts: 709

Kudos [?]: 148 [0], given: 42

Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 17:55
10y+x = 9+10x+y
=> y = 1+x

Answer E.

Kudos [?]: 148 [0], given: 42

TOEFL Forum Moderator
avatar
Joined: 16 Nov 2010
Posts: 1586

Kudos [?]: 607 [0], given: 40

Location: United States (IN)
Concentration: Strategy, Technology
Premium Member Reviews Badge
Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 18:21
10y + x = 10x + y + 9

=> 9y - 9x = 9

=> y = x + 1

Answer - E
_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings

Kudos [?]: 607 [0], given: 40

Manager
Manager
avatar
Joined: 11 Dec 2010
Posts: 115

Kudos [?]: 48 [0], given: 50

WE: Consulting (Consulting)
Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 05 Apr 2011, 18:26
Whenever the digits of two digit numbers are reversed, the difference between the digits of the number is mod(tens-units digits)*9... Check the multiplication table of 9...

So if the number increases by 9, then difference between them is 1... check 45...54-45=9

So y=x+1

Kudos [?]: 48 [0], given: 50

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 14951

Kudos [?]: 287 [0], given: 0

Premium Member
Re: If the tens digit x and the units digit y of a positive integer n are [#permalink]

Show Tags

New post 09 Aug 2017, 12:37
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Kudos [?]: 287 [0], given: 0

Re: If the tens digit x and the units digit y of a positive integer n are   [#permalink] 09 Aug 2017, 12:37
Display posts from previous: Sort by

If the tens digit x and the units digit y of a positive integer n are

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.