What is the units digit of positive integer x? : Data Sufficiency (DS)

My Profile Logout

Test's Subscription Expires:

My Follow Feed Kudos My Error Log

Messages and Replies

Settings Mark All Read

See All

Applicant Notifications

Settings Mark All Read

See All

Global notifications

Settings Mark All Read

See All

What is the units digit of positive integer x?

Sort by Date

Sort by Kudos

Author

Message

TAGS:

Hide Tags

Math Expert

Joined: 02 Sep 2009

Posts: 52146

What is the units digit of positive integer x? [#permalink]

Show Tags

27 Apr 2016, 22:34

00:00

Difficulty:

75% (hard)

Question Stats:

47% (01:34) correct

53% (02:04) wrong

based on 109 sessions

HideShow timer Statistics

What is the units digit of positive integer x?

(1) 7, 15, 24, and n are all factors of x.
(2) 6! < x < 7!

Spoiler: OA

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.

What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Current Student

Status: It`s Just a pirates life !

Joined: 21 Mar 2014

Posts: 231

Location: India

Concentration: Strategy, Operations

Schools: Ross '19 (A), ISB '18 (D), Rotman '19 (D), NUS '19 (S), NTU '18 (D)

GMAT 1: 690 Q48 V36

GPA: 4

WE: Consulting (Manufacturing)

Re: What is the units digit of positive integer x? [#permalink]

Show Tags

27 Apr 2016, 22:57

Bunuel wrote:

What is the units digit of positive integer x?

(1) 7, 15, 24, and n are all factors of x.
(2) 6! < x < 7!

B is out straight away

A tells that number can end in 0/5

C is the answer i believe'
_________________

Aiming for a 3 digit number with 7 as hundredths Digit

Math Expert

Joined: 02 Aug 2009

Posts: 7200

Re: What is the units digit of positive integer x? [#permalink]

Show Tags

27 Apr 2016, 23:30

Balajikarthick1990 wrote:

Bunuel wrote:

What is the units digit of positive integer x?

(1) 7, 15, 24, and n are all factors of x.
(2) 6! < x < 7!

B is out straight away

A tells that number can end in 0/5

C is the answer i believe'

HI,
Always be careful while eliminating a statement..
what is statement I
(1) 7, 15, 24, and n are all factors of x.
the factors are 15 and 24, so x will be a MULTIPLE of 5 and 2..
thus UNIT's digit will be 0
Suff
ans A
_________________

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

Status: It`s Just a pirates life !

Joined: 21 Mar 2014

Posts: 231

Location: India

Concentration: Strategy, Operations

Schools: Ross '19 (A), ISB '18 (D), Rotman '19 (D), NUS '19 (S), NTU '18 (D)

GMAT 1: 690 Q48 V36

GPA: 4

WE: Consulting (Manufacturing)

Re: What is the units digit of positive integer x? [#permalink]

Show Tags

27 Apr 2016, 23:32

chetan2u wrote:

Balajikarthick1990 wrote:

Bunuel wrote:

What is the units digit of positive integer x?

(1) 7, 15, 24, and n are all factors of x.
(2) 6! < x < 7!

B is out straight away

A tells that number can end in 0/5

C is the answer i believe'

Ya agreed sir...will be careful.
_________________

Aiming for a 3 digit number with 7 as hundredths Digit

Current Student

Joined: 12 Aug 2015

Posts: 2626

Schools: Boston U '20 (M)

GRE 1: Q169 V154

Re: What is the units digit of positive integer x? [#permalink]

Show Tags

19 Nov 2016, 01:47

Since x is divisible by both 15 and 24 from statement 1 we can say that unit digit of x must be zero.
Again statement 2 is not sufficient as we don't know what x might be.
hence A
_________________

Give me a hell yeah ...!!!!!

MBA Dating:- B-SCHOOL with the MOST ATTRACTIVE Women

MBA Recruiting:- EMPLOYMENT AND SALARY STATISTICS AT TOP B-SCHOOLS IN THE US! (2018)

MBA Financing:- INDIAN PUBLIC BANKS vs PRODIGY FINANCE!

Getting into HOLLYWOOD with an MBA!

The MOST AFFORDABLE MBA programs!

STONECOLD's BRUTAL Mock Tests for GMAT-Quant(700+)

AVERAGE GRE Scores At The Top Business Schools!

Current Student

Joined: 12 Aug 2015

Posts: 2626

Schools: Boston U '20 (M)

GRE 1: Q169 V154

Re: What is the units digit of positive integer x? [#permalink]

Show Tags

24 Nov 2016, 03:44

Great Question.
Here we need the units digit of x
Statement 1=>
this statement tells us that 5 and 2 must be prime factors of x.
Hence the units digit of x must be zero.
Hence Sufficient.

Statement 2
x must lie between (720,720*7)
Not sufficient

Hence A
_________________

Give me a hell yeah ...!!!!!

MBA Dating:- B-SCHOOL with the MOST ATTRACTIVE Women

MBA Recruiting:- EMPLOYMENT AND SALARY STATISTICS AT TOP B-SCHOOLS IN THE US! (2018)

Non-Human User

Joined: 09 Sep 2013

Posts: 9407

Re: What is the units digit of positive integer x? [#permalink]

Show Tags

26 Aug 2018, 02:24

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.
_________________