Last visit was: 28 Apr 2026, 09:11 It is currently 28 Apr 2026, 09:11
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Events & Promotions
Back to Forum
Create Topic
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 28 Apr 2026
Posts: 109,949
Own Kudos:
811,732
Given Kudos: 105,927
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,949
Kudos: 811,732
If x is a two-digit number (so x = ba with b and a digits), what is th 22 Oct 2017, 06:37
Kudos
Add Kudos
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

65% (hard)

Question Stats:

54% (01:46) correct 46% (01:50) wrong based on 102 sessions

History

Date
Time
Result
Not Attempted Yet
If x is a two-digit number (so x = ba with b and a digits), what is the last digit a of x?

(1) The number 3x is a three-digit number whose last digit is a.
(2) The digit a is less than 7.
ShowHide Answer
Official Answer
E
User avatar
niks18
User avatar
Retired Moderator
Joined: 25 Feb 2013
Last visit: 30 Jun 2021
Posts: 862
Own Kudos:
1,806
Given Kudos: 54
Location: India
GPA: 3.82
Products:
My Reviews
Posts: 862
Kudos: 1,806
If x is a two-digit number (so x = ba with b and a digits), what is th Updated on: 22 Oct 2017, 07:56
Originally posted by niks18 on 22 Oct 2017, 07:19.
Last edited by niks18 on 22 Oct 2017, 07:56, edited 2 times in total.
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
If x is a two-digit number (so x = ba with b and a digits), what is the last digit a of x?

(1) The number 3x is a three-digit number whose last digit is a.
(2) The digit a is less than 7.
Show more

We need unit's digit of \(x\)

Statement 1: implies that unit's digit of \(x\) is \(0\) or \(5\) because \(0\) multiplied by \(3\) unit's digit will be \(0\) and \(5\) multiplied by \(3\) unit's digit will be \(5\). Hence insufficient

Statement 2: \(a\) could be any number less than \(7\). Insufficient

Combining 1 & 2 again \(a\) can be \(0\) or \(5\). Insufficient

Option E
User avatar
souvonik2k
User avatar
Retired Moderator
Joined: 25 Nov 2015
Last visit: 05 Dec 2021
Posts: 949
Own Kudos:
2,249
 [1]
Given Kudos: 751
Status:Preparing for GMAT
Location: India
GPA: 3.64
Products:
My Reviews
Posts: 949
Kudos: 2,249
 [1]
If x is a two-digit number (so x = ba with b and a digits), what is th 22 Oct 2017, 07:47
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
S1- 3x is a three-digit number whose last digit is a.
For example, no. can be 35, 40, 45,... which when multiplied by 3, gives 105, 120, 135...and so on.
Not sufficient.

S2 - The digit a is less than 7. Many possibilities.
Not sufficient.

Combining, also not sufficient as both 0 and 5 are less than 7.
Answer E.

Please give kudos, if u liked my post!
avatar
reachskishore
avatar
Joined: 21 Nov 2016
Last visit: 19 Dec 2018
Posts: 36
Own Kudos:
32
Given Kudos: 23
Posts: 36
Kudos: 32
If x is a two-digit number (so x = ba with b and a digits), what is th 23 Oct 2017, 03:00
Kudos
Add Kudos
Bookmarks
Bookmark this Post
While I agree with the answer, I do not think that the approach used here is correct.
The stem says x is a two-digit number, I am not getting why are you guys considering it to be a multiple of 5?
Stmt 1 says, X when multiplied with 3 will yield a 3 digit number. So X could be anything above 33.
Because 3 times 33 will give 99 and any 2 digit number above this will yield more than 2 digits when multiplied by 3.
So, from stmt 1, X has a lot of options. Hence insufficient.

Coming to stmt 2, it says a < 7 , meaning, the last digit of 3X is less than 7. Insuff.

1 + 2. take number 34, 3*34 = 102.
take number 35, 3*35 = 105.
take number 36, 3*36 = 108, last digit exceeds 7.
So, we are left out with 2 results 102 and 105 whose last digits are below 7. i.e., we have 2 options for X, 34 & 35.
Multiple answers, So both stmts are insuff.

Hence E.

Still, I would like to know how you guys considered X to be a multiple of 5. Please let me know if there is any logic that I might have missed while analyzing the stem.
User avatar
souvonik2k
User avatar
Retired Moderator
Joined: 25 Nov 2015
Last visit: 05 Dec 2021
Posts: 949
Own Kudos:
2,249
 [1]
Given Kudos: 751
Status:Preparing for GMAT
Location: India
GPA: 3.64
Products:
My Reviews
Posts: 949
Kudos: 2,249
 [1]
If x is a two-digit number (so x = ba with b and a digits), what is th 23 Oct 2017, 04:01
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
reachskishore
While I agree with the answer, I do not think that the approach used here is correct.
The stem says x is a two-digit number, I am not getting why are you guys considering it to be a multiple of 5?
Stmt 1 says, X when multiplied with 3 will yield a 3 digit number. So X could be anything above 33.
Because 3 times 33 will give 99 and any 2 digit number above this will yield more than 2 digits when multiplied by 3.
So, from stmt 1, X has a lot of options. Hence insufficient.

Coming to stmt 2, it says a < 7 , meaning, the last digit of 3X is less than 7. Insuff.

1 + 2. take number 34, 3*34 = 102.
take number 35, 3*35 = 105.
take number 36, 3*36 = 108, last digit exceeds 7.
So, we are left out with 2 results 102 and 105 whose last digits are below 7. i.e., we have 2 options for X, 34 & 35.
Multiple answers, So both stmts are insuff.

Hence E.

Still, I would like to know how you guys considered X to be a multiple of 5. Please let me know if there is any logic that I might have missed while analyzing the stem.
Show more

Since x=ba which when multiplied by 3 gives 3 digit number with last digit a, the only possibilities are a=0 or 5 . 0 and 5 are the only digits which when multiplied by 3 gives last digit 0 or 5.
Hope it is clear.
avatar
reachskishore
avatar
Joined: 21 Nov 2016
Last visit: 19 Dec 2018
Posts: 36
Own Kudos:
32
Given Kudos: 23
Posts: 36
Kudos: 32
If x is a two-digit number (so x = ba with b and a digits), what is th 24 Oct 2017, 00:03
Kudos
Add Kudos
Bookmarks
Bookmark this Post
souvonik2k
reachskishore
While I agree with the answer, I do not think that the approach used here is correct.
The stem says x is a two-digit number, I am not getting why are you guys considering it to be a multiple of 5?
Stmt 1 says, X when multiplied with 3 will yield a 3 digit number. So X could be anything above 33.
Because 3 times 33 will give 99 and any 2 digit number above this will yield more than 2 digits when multiplied by 3.
So, from stmt 1, X has a lot of options. Hence insufficient.

Coming to stmt 2, it says a < 7 , meaning, the last digit of 3X is less than 7. Insuff.

1 + 2. take number 34, 3*34 = 102.
take number 35, 3*35 = 105.
take number 36, 3*36 = 108, last digit exceeds 7.
So, we are left out with 2 results 102 and 105 whose last digits are below 7. i.e., we have 2 options for X, 34 & 35.
Multiple answers, So both stmts are insuff.

Hence E.

Still, I would like to know how you guys considered X to be a multiple of 5. Please let me know if there is any logic that I might have missed while analyzing the stem.

Since x=ba which when multiplied by 3 gives 3 digit number with last digit a, the only possibilities are a=0 or 5 . 0 and 5 are the only digits which when multiplied by 3 gives last digit 0 or 5.
Hope it is clear.
Show more

Oh yes !!! Had missed that detail. Sorry about that.
Thanks for clearing out my doubt.

+1Kudos to you
Moderators:
Bunuel
Math Expert
109949 posts
kingbucky
498 posts
Gmat860sanskar
212 posts