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

It is currently 23 Aug 2014, 03:57

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

What is the units digit of Y?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Current Student
avatar
Joined: 26 May 2005
Posts: 571
Followers: 18

Kudos [?]: 105 [0], given: 13

GMAT Tests User
What is the units digit of Y? [#permalink] New post 29 Jun 2011, 00:25
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

62% (01:45) correct 38% (00:16) wrong based on 29 sessions
Q: What is the units digit of Y?
st:1 The units digit of Y^2 is equal to 6.
St:2 The units digit of (Y+1)^2 is equal to 5


Its fairly simple problem , but I have a problem with the OA.
St1: can be 4 or 6 or - 4 or -6 ... hence in sufficient
st2: can be 4 or -6... .. The question doesnt mention the Y is a postive integer..
[Reveal] Spoiler: OA
Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 2048
Followers: 128

Kudos [?]: 899 [0], given: 376

GMAT Tests User
Re: Digits - MGMAT Adv Quant [#permalink] New post 29 Jun 2011, 02:56
sudhir18n wrote:
Q: What is the units digit of Y?
st:1 The units digit of Y^2 is equal to 6.
St:2 The units digit of (Y+1)^2 is equal to 5


Its fairly simple problem , but I have a problem with the OA.
St1: can be 4 or 6 or - 4 or -6 ... hence in sufficient
st2: can be 4 or -6... .. The question doesnt mention the Y is a postive integer..


Good catch!!! Stem should have mentioned "positive integer Y", OR the OA should be "E". Please notify them.
_________________

~fluke

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
User avatar
Joined: 29 Jun 2011
Posts: 76
Followers: 3

Kudos [?]: 11 [0], given: 47

Re: Digits - MGMAT Adv Quant [#permalink] New post 30 Jun 2011, 00:24
no need to mention positive integer...the question says find "units digit". by definition, units digits can only be non negative integers. so there is no ambiguity.
_________________

It matters not how strait the gate,
How charged with punishments the scroll,
I am the master of my fate :
I am the captain of my soul.
~ William Ernest Henley


Last edited by fivedaysleft on 02 Jul 2011, 10:57, edited 1 time in total.
Current Student
avatar
Joined: 26 May 2005
Posts: 571
Followers: 18

Kudos [?]: 105 [0], given: 13

GMAT Tests User
Re: Digits - MGMAT Adv Quant [#permalink] New post 30 Jun 2011, 01:58
[quote="fivedaysleft"]no need to mention positive integer...the question says find "units digit". by definition, units digits can only be positve integers. so there is no ambiguity.

quote]

Can anyone confirm this? I'm not aware of any such rule.
Manager
Manager
avatar
Joined: 23 Jan 2011
Posts: 128
Followers: 1

Kudos [?]: 9 [0], given: 12

Re: Digits - MGMAT Adv Quant [#permalink] New post 30 Jun 2011, 02:15
I think b is the correct answer. At first even I went for E but a second read of the question says unit digit of Y- so has to be positive. Else the question could be what is Y?

So solution could be as follows:
1) Could be 4 or 6- A and D are out
2) has to be 4- sufficient, B is the answer.

B
Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 2048
Followers: 128

Kudos [?]: 899 [0], given: 376

GMAT Tests User
Re: Digits - MGMAT Adv Quant [#permalink] New post 30 Jun 2011, 02:18
sudhir18n wrote:
fivedaysleft wrote:
no need to mention positive integer...the question says find "units digit". by definition, units digits can only be positve integers. so there is no ambiguity.


Can anyone confirm this? I'm not aware of any such rule.


fivedaysleft mentioned a partially correct rule. Digit=0,1,2,3,4,5,6,7,8,9 (So a digit is non-negative one-digit integer)

But, note that y is an Integer, any Integer, NOT necessarily a digit.

Unit's digit of "y" is a digit.

y can be -525324324342424246; Here unit's digit of y=6
OR
y can be +434252424242424244; Here unit's digit of y=4

Please send a mail to MGMAT and get it clarified.
_________________

~fluke

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
User avatar
Joined: 29 Jun 2011
Posts: 76
Followers: 3

Kudos [?]: 11 [0], given: 47

Re: Digits - MGMAT Adv Quant [#permalink] New post 02 Jul 2011, 11:00
fluke wrote:
y can be -525324324342424246; Here unit's digit of y=6
OR
y can be +434252424242424244; Here unit's digit of y=4

Please send a mail to MGMAT and get it clarified.


i dont think the ambiguity is too great.
because if a problem is given on the number -525324324342424246
it can always be assigned as (-1)*(525324324342424246) and we can proceed. There might be a difference in definitions of digits and integers at the fundamental level but is it necessary for GMAT? i do not believe so.
correct me if i am wrong. :?
_________________

It matters not how strait the gate,
How charged with punishments the scroll,
I am the master of my fate :
I am the captain of my soul.
~ William Ernest Henley

Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 2048
Followers: 128

Kudos [?]: 899 [0], given: 376

GMAT Tests User
Re: Digits - MGMAT Adv Quant [#permalink] New post 02 Jul 2011, 11:25
fivedaysleft wrote:
fluke wrote:
y can be -525324324342424246; Here unit's digit of y=6
OR
y can be +434252424242424244; Here unit's digit of y=4

Please send a mail to MGMAT and get it clarified.


i dont think the ambiguity is too great.
because if a problem is given on the number -525324324342424246
it can always be assigned as (-1)*(525324324342424246) and we can proceed. There might be a difference in definitions of digits and integers at the fundamental level but is it necessary for GMAT? i do not believe so.
correct me if i am wrong. :?


If we can find one such ambiguity in OG's OR GmatPrep, then we can think about taking it for granted. It is highly unlikely that GMAT will ever frustrate you with such dilemma. Skip this question and let's wait for MGMAT's response.
_________________

~fluke

Get the best GMAT Prep Resources with GMAT Club Premium Membership

1 KUDOS received
GMAT Instructor
avatar
Joined: 24 Jun 2008
Posts: 967
Location: Toronto
Followers: 253

Kudos [?]: 653 [1] , given: 3

GMAT Tests User
Re: Digits - MGMAT Adv Quant [#permalink] New post 03 Jul 2011, 03:53
1
This post received
KUDOS
On the real GMAT, any question about units digits will be restricted to *positive* numbers only. So if this were an actual GMAT question, the stem would tell you that Y is positive. I agree that this question is ambiguous as written and needs to be corrected, but if you understand how you'd solve the question if it read "If Y is a positive integer, what it the units digit of Y?" then you've taken away everything you need to take away from the problem.
_________________

Nov 2011: After years of development, I am now making my advanced Quant books and high-level problem sets available for sale. Contact me at ianstewartgmat at gmail.com for details.

Private GMAT Tutor based in Toronto

Re: Digits - MGMAT Adv Quant   [#permalink] 03 Jul 2011, 03:53
    Similar topics Author Replies Last post
Similar
Topics:
4 What is the Units digit of Y vomhorizon 6 11 Nov 2012, 00:42
In-action problem set: 5. what is the units digit of y? 1) karthiksms 10 10 Oct 2011, 21:07
1 What is the unit digit?? Hussain15 5 31 Oct 2009, 07:26
What's the units digit Questions? Liquid 5 31 Mar 2008, 16:09
If the tens digit x and the units digit y of a positive Avis 2 26 Feb 2006, 09:43
Display posts from previous: Sort by

What is the units digit of Y?

  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®.