Please help

This topic has expert replies
Newbie | Next Rank: 10 Posts
Posts: 7
Joined: Sun Feb 19, 2012 6:28 am

Please help

by GMATbeater12 » Sat Feb 25, 2012 4:57 pm
XY times YX equals XZX, where X, Y, and Z are three different nonzero digits. If X times Y is less than ten, what is the two-digit number XY?

(A) 11
(B) 12
(C) 13
(D) 21
(E) 31

User avatar
Community Manager
Posts: 1060
Joined: Fri May 13, 2011 6:46 am
Location: Utrecht, The Netherlands
Thanked: 318 times
Followed by:52 members

by neelgandham » Sat Feb 25, 2012 5:49 pm
XY times YX equals XZX, where X, Y, and Z are three different nonzero digits. If X times Y is less than ten, what is the two-digit number XY?

(A) 11 - Because X,Y are different non-zero digits and which is not the case with this option, this option is incorrect.
(B) 12 - The Unit's digit of XY*YX should be X. Because the Unit's digit of 12*21 is 2, which is not equal to x(=1),this option is incorrect.
(C) 13 - The Unit's digit of XY*YX should be X. Because the Unit's digit of 13*31 is 3, which is not equal to x(=1),this option is incorrect.
(D) 21 - 21*12(XY*YX)= 252 =(XZX) - Bingo! Correct!
(E) 31 - Forget it

IMO D
Anil Gandham
Welcome to BEATtheGMAT | Photography | Getting Started | BTG Community rules | MBA Watch
Check out GMAT Prep Now's online course at https://www.gmatprepnow.com/

Master | Next Rank: 500 Posts
Posts: 382
Joined: Thu Mar 31, 2011 5:47 pm
Thanked: 15 times

by ArunangsuSahu » Wed Feb 29, 2012 12:31 pm
Go By Options

(D)

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Wed Feb 29, 2012 9:18 pm
GMATbeater12 wrote:XY times YX equals XZX, where X, Y, and Z are three different nonzero digits. If X times Y is less than ten, what is the two-digit number XY?

(A) 11
(B) 12
(C) 13
(D) 21
(E) 31
XY * YX = XZX
X * Y < 10

(A) If XY = 11, then YX = 11, but since X, Y are different nonzero digits, so this is not the correct choice.

(B) If XY = 12, then YX = 21. So, XY * YX = 12 * 21 = 252 (= XZX), which cannot be true as X = 1 and XZZX = 252 implies X = 2, which is a contradiction. Again this is not the correct choice.

(C) If XY = 13, then YX = 31, So, XY * YX = 13 * 31 = 403, cannot be true as the units and hundreds digit should be the same in XZX.

(D)If XY = 21, then YX = 12. So, XY * YX = 21 * 12 = 252 (= XZX), which holds true.

The correct answer is D.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/

User avatar
Senior | Next Rank: 100 Posts
Posts: 58
Joined: Thu Sep 29, 2011 5:15 am
Thanked: 7 times
Followed by:1 members
GMAT Score:740

by kul512 » Fri Mar 02, 2012 11:14 am
Easiest way to solve is through answers-

A can not be answer as X and Y are different digits.

we have 12 and 13 to check as it will automaticaly check 21 and 31.


so 12X21=252, So if we choose 21 as XY then XY and YX multiplied generates a number XZX.

so 21 is the answer.D[/spoiler]
Sometimes there is very fine line between right and wrong: perspective.