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

It is currently 14 Oct 2019, 03:39

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.

Close

Request Expert Reply

Confirm Cancel

What is the least common multiple of 6, 12, 20, 30 and 42?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 8001
GMAT 1: 760 Q51 V42
GPA: 3.82
What is the least common multiple of 6, 12, 20, 30 and 42?  [#permalink]

Show Tags

New post 24 Jan 2018, 01:36
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

89% (01:30) correct 11% (00:43) wrong based on 59 sessions

HideShow timer Statistics

[GMAT math practice question]

What is the least common multiple of 6, 12, 20, 30 and 42?

A. 120
B. 180
C. 240
D. 360
E. 420

_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $79 for 1 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"
Math Expert
avatar
V
Joined: 02 Aug 2009
Posts: 7952
Re: What is the least common multiple of 6, 12, 20, 30 and 42?  [#permalink]

Show Tags

New post 24 Jan 2018, 02:15
MathRevolution wrote:
[GMAT math practice question]

What is the least common multiple of 6, 12, 20, 30 and 42?

A. 120
B. 180
C. 240
D. 360
E. 420



A straight answer..
42 is the biggest number amongst all 5 numbers and the answer has to be a MULTIPLE of 42 and should have a 0 in the units digit..
Answer canbe 42*5=210(not given) and next 42*10=420..given
E

Otherwise proper method
6=2*3...
\(12=2^2*3\)..
\(20=2^2*5\)..
\(30=2*3*5\)..
\(42=2*3*7\)..
Take max power of each PRIME factor.
LCM=\(2^2*3*5*7=420\)
E
_________________
Board of Directors
User avatar
D
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4751
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User
Re: What is the least common multiple of 6, 12, 20, 30 and 42?  [#permalink]

Show Tags

New post 24 Jan 2018, 02:39
MathRevolution wrote:
[GMAT math practice question]

What is the least common multiple of 6, 12, 20, 30 and 42?

A. 120
B. 180
C. 240
D. 360
E. 420

Check the options provided is straight (E) as reached by chetan2u
_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
Intern
Intern
avatar
B
Joined: 03 Nov 2017
Posts: 12
GMAT 1: 590 Q48 V23
Re: What is the least common multiple of 6, 12, 20, 30 and 42?  [#permalink]

Show Tags

New post 24 Jan 2018, 18:46
1
210 cannot be answer chetan, 210 is not divisible by 12

Sent from my SM-G955U using GMAT Club Forum mobile app
CEO
CEO
User avatar
V
Joined: 12 Sep 2015
Posts: 3990
Location: Canada
Re: What is the least common multiple of 6, 12, 20, 30 and 42?  [#permalink]

Show Tags

New post 24 Jan 2018, 18:52
Top Contributor
adityanahan wrote:
210 cannot be answer chetan, 210 is not divisible by 12

Sent from my SM-G955U using GMAT Club Forum mobile app


??
210 is not among the answer choices :-)
_________________
Test confidently with gmatprepnow.com
Image
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 8001
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: What is the least common multiple of 6, 12, 20, 30 and 42?  [#permalink]

Show Tags

New post 26 Jan 2018, 01:19
=>

These numbers have the following prime factorizations:
\(6 = 2^1*3^1, 12 = 2^2*3^1, 20 = 2^2*5^1, 30 = 2^1*3^1*5^1\) and \(42 = 2^13^17^1\)

In order to find their LCM, we multiply together each of the primes, raised to their maximum exponents found in the above prime factorizations.
The LCM of the numbers is \(2^2*3^1*5^1*7^1 = 420\) since the maximum exponent of \(2\) is \(2\), the maximum exponent of \(3\) is \(1\), the maximum exponent of \(5\) is \(1\) and the maximum exponent of \(7\) is \(1\).

Therefore, the answer is E.

Answer: E
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $79 for 1 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2817
Re: What is the least common multiple of 6, 12, 20, 30 and 42?  [#permalink]

Show Tags

New post 26 Jan 2018, 10:37
MathRevolution wrote:
[GMAT math practice question]

What is the least common multiple of 6, 12, 20, 30 and 42?

A. 120
B. 180
C. 240
D. 360
E. 420


Let’s prime factorize each value:

6 = 2 x 3

12 = 2^2 x 3

20 = 2^2 x 5

30 = 2 x 3 x 5

42 = 2 x 3 x 7

Multiplying together each unique prime factor (raised to the largest power), we have:

2^2 x 3 x 5 x 7 = 420

Answer: E
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

GMAT Club Bot
Re: What is the least common multiple of 6, 12, 20, 30 and 42?   [#permalink] 26 Jan 2018, 10:37
Display posts from previous: Sort by

What is the least common multiple of 6, 12, 20, 30 and 42?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne