GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 24 Sep 2018, 12:30

### 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

# D01-12

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Aug 2009
Posts: 6808

### Show Tags

05 May 2016, 08:51
amilbusthon wrote:
I think this is a poor-quality question and I don't agree with the explanation. (2) @@ is divisible by 9. can be 0 or 9 (note that zero is divisible by every integer except zero itself). Not sufficient. So it could be 12340 or 12349 but these are not divisible by 9. It should be 12348, because the sum of 1+2+3+4+8 is divisible by 9.

The statement talks of @, the units digit, to be div by 9 so it has to be 0 or 9..
why are you confusing it with 1234@ being div by 9..
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

GMAT online Tutor

Current Student
Joined: 12 Oct 2012
Posts: 116
WE: General Management (Other)

### Show Tags

27 Jul 2016, 14:09
I think this is a high-quality question and I agree with explanation.
Intern
Joined: 01 Jun 2016
Posts: 6
Location: Brazil
GMAT 1: 600 Q42 V31
GPA: 3

### Show Tags

08 Aug 2016, 20:18
Hello, regardin the first condition, why @ can't be 6 or 7? both ! are not divisible by 5.

thanks
Math Expert
Joined: 02 Sep 2009
Posts: 49430

### Show Tags

09 Aug 2016, 01:43
mounirbr wrote:
Hello, regardin the first condition, why @ can't be 6 or 7? both ! are not divisible by 5.

thanks

6! = 1*2*3*4*5*6 = 720, which IS divisible by 5;
7! = 1*2*3*4*5*6*7 = 5040, which IS divisible by 5.
_________________
Intern
Joined: 03 Jun 2014
Posts: 6
Location: Australia
Concentration: Strategy, Technology
GPA: 3.01
WE: Information Technology (Consulting)

### Show Tags

10 Feb 2017, 21:19
This s an excellent question, tests logic very well and if done right, saves quite a bit time.
Intern
Joined: 14 Feb 2017
Posts: 7

### Show Tags

06 Mar 2017, 21:16
(1) @! is not divisible by 5. Can be 0, 1, 2, 3, or 4 (note that 0!=1). Not sufficient.

(2) @ is divisible by 9. Can be 0 or 9 (note that zero is divisible by every integer except zero itself). Not sufficient.

(1)+(2) Intersection of the values for @ from (1) and (2) is @=0. Sufficient.

Can someone please explain (1) to me? How is it that 0! works if it meets the criteria that it is NOT divisible by 5? You can divide 0/5. So that means @ would have to equal 1, 2 3, or 4. Which means that combining 1& 2 wouldn't work and answer would be E.

Getting lost on this point...thank you!
Math Expert
Joined: 02 Sep 2009
Posts: 49430

### Show Tags

07 Mar 2017, 02:33
bananasss wrote:
(1) @! is not divisible by 5. Can be 0, 1, 2, 3, or 4 (note that 0!=1). Not sufficient.

(2) @ is divisible by 9. Can be 0 or 9 (note that zero is divisible by every integer except zero itself). Not sufficient.

(1)+(2) Intersection of the values for @ from (1) and (2) is @=0. Sufficient.

Can someone please explain (1) to me? How is it that 0! works if it meets the criteria that it is NOT divisible by 5? You can divide 0/5. So that means @ would have to equal 1, 2 3, or 4. Which means that combining 1& 2 wouldn't work and answer would be E.

Getting lost on this point...thank you!

(1) says that @! (factorial of number @) is NOT divisible by 5. can be 0 because @! = 0! = 1 and 1 is NOT divisible by 5.
_________________
Intern
Joined: 14 Feb 2017
Posts: 7

### Show Tags

07 Mar 2017, 08:59
Bunuel wrote:
bananasss wrote:
(1) @! is not divisible by 5. Can be 0, 1, 2, 3, or 4 (note that 0!=1). Not sufficient.

(2) @ is divisible by 9. Can be 0 or 9 (note that zero is divisible by every integer except zero itself). Not sufficient.

(1)+(2) Intersection of the values for @ from (1) and (2) is @=0. Sufficient.

Can someone please explain (1) to me? How is it that 0! works if it meets the criteria that it is NOT divisible by 5? You can divide 0/5. So that means @ would have to equal 1, 2 3, or 4. Which means that combining 1& 2 wouldn't work and answer would be E.

Getting lost on this point...thank you!

(1) says that @! (factorial of number @) is NOT divisible by 5. be 0 because @! = 0! = 1 and 1 is NOT divisible by 5.

OK brilliant thank you...Had no idea 0!=1, which changes everything, of course.
Intern
Joined: 22 May 2017
Posts: 4

### Show Tags

15 Jun 2017, 06:54
@ is divisible by 9

You have to be very careful in GMAT. It is such a small thing to overlook.
Intern
Joined: 20 May 2016
Posts: 1

### Show Tags

01 Jul 2017, 08:01
Bunnel
The question stem tells us that @ is either (0 or 5) as N is divisible by 5 .
I Think we can get a unique answer with statement A because 1 is not divisible by 5 whereas 5! is divisible by 5 .
I cannot understand why you have checked for @ {1,2,3,4} as we have already narrowed our search down to @{0,5}.
Math Expert
Joined: 02 Sep 2009
Posts: 49430

### Show Tags

01 Jul 2017, 09:21
akshaypareek312 wrote:
Bunnel
The question stem tells us that @ is either (0 or 5) as N is divisible by 5 .
I Think we can get a unique answer with statement A because 1 is not divisible by 5 whereas 5! is divisible by 5 .
I cannot understand why you have checked for @ {1,2,3,4} as we have already narrowed our search down to @{0,5}.

You should read question and solution more carefully. The question does NOT say that @ equals to 0 or 5. The question asks whether @ equals to 0 or 5. From (1) if @ is 0, then the answer to the question is YES but if @ is 1, 2, 3, or 4, then the answer to the question is NO.
_________________
Intern
Joined: 09 Dec 2015
Posts: 6

### Show Tags

02 Oct 2017, 21:01
I think this is a poor-quality question and I don't agree with the explanation. wrong answer
Math Expert
Joined: 02 Sep 2009
Posts: 49430

### Show Tags

02 Oct 2017, 21:04
amar.igtr wrote:
I think this is a poor-quality question and I don't agree with the explanation. wrong answer

The question is 100% correct. I suggest to read carefully the solution and the whole thread once more. If you still have questions you are welcome to post.
_________________
Intern
Joined: 27 Aug 2016
Posts: 13
Location: India
GMAT 1: 730 Q41 V49
GPA: 3.96

### Show Tags

17 Oct 2017, 20:19
I think this is a high-quality question and I agree with explanation.
Intern
Joined: 10 Feb 2017
Posts: 7

### Show Tags

19 Nov 2017, 06:46
I think this is a high-quality question and I agree with explanation.
Intern
Joined: 05 Feb 2017
Posts: 3

### Show Tags

25 Nov 2017, 02:48
I think this is a high-quality question and I agree with explanation.
Manager
Joined: 30 Mar 2017
Posts: 136
GMAT 1: 200 Q1 V1

### Show Tags

19 May 2018, 12:46
Bunuel wrote:
If $$N = 1234@$$ and $$@$$ represents the units digit of $$N$$, is $$N$$ a multiple of 5?

(1) $$@!$$ is not divisible by 5

(2) $$@$$ is divisible by 9

This is a great question.
Intern
Joined: 08 Dec 2012
Posts: 1

### Show Tags

19 Sep 2018, 01:38
@! is not divisible by 5. can be 0, 1, 2, 3, or 4 (note that 0!=1). Not sufficient.
Here N's Unit Digit is https://gmatclub.com:443/forum/memberlist.php?mode=viewprofile&un=, not @! so why you consider 0 here ... can be 1,2,3,4 only..
Math Expert
Joined: 02 Sep 2009
Posts: 49430

### Show Tags

19 Sep 2018, 02:47
ARVINDSHARMA wrote:
@! is not divisible by 5. can be 0, 1, 2, 3, or 4 (note that 0!=1). Not sufficient.
Here N's Unit Digit is https://gmatclub.com:443/forum/memberlist.php?mode=viewprofile&un=, not @! so why you consider 0 here ... can be 1,2,3,4 only..

0! = 1, which is NOT divisible by 5. So, $$@$$ be 0.
_________________
D01-12 &nbs [#permalink] 19 Sep 2018, 02:47

Go to page   Previous    1   2   [ 39 posts ]

Display posts from previous: Sort by

# D01-12

Moderators: chetan2u, Bunuel

## Events & Promotions

 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®.