Last visit was: 29 Apr 2024, 09:03 It is currently 29 Apr 2024, 09:03

Close

GRE Prep 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 GRE 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
User avatar
Retired Moderator
Joined: 07 Jun 2014
Posts: 4810
Own Kudos [?]: 10617 [10]
Given Kudos: 0
GRE 1: Q167 V156
WE:Business Development (Energy and Utilities)
Send PM
Most Helpful Expert Reply
User avatar
Retired Moderator
Joined: 07 Jun 2014
Posts: 4810
Own Kudos [?]: 10617 [5]
Given Kudos: 0
GRE 1: Q167 V156
WE:Business Development (Energy and Utilities)
Send PM
General Discussion
avatar
Intern
Intern
Joined: 02 Aug 2018
Posts: 1
Own Kudos [?]: 4 [3]
Given Kudos: 0
Send PM
Intern
Intern
Joined: 27 Apr 2021
Posts: 3
Own Kudos [?]: 1 [0]
Given Kudos: 11
Send PM
Re: If n is an integer and n3 is divisible by 24, what is the la [#permalink]
SAHITHI97 wrote:
why 6 but not 12?


Posted from my mobile device
Intern
Intern
Joined: 30 Aug 2021
Posts: 25
Own Kudos [?]: 10 [0]
Given Kudos: 12
Send PM
Re: If n is an integer and n3 is divisible by 24, what is the la [#permalink]
please explain this once again i didnt understand why 6
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Own Kudos [?]: 11694 [3]
Given Kudos: 136
Send PM
If n is an integer and n3 is divisible by 24, what is the la [#permalink]
2
1
Bookmarks
sandy wrote:
If n is an integer and \(n^3\) is divisible by 24, what is the largest number that must be a factor of n?

(A) 1
(B) 2
(C) 6
(D) 8
(E) 12

-----ASIDE---------------------
A lot of integer property questions can be solved using prime factorization.
For questions involving divisibility, divisors, factors and multiples, we can say:
If N is divisible by k, then k is "hiding" within the prime factorization of N

Consider these examples:
24 is divisible by 3 because 24 = (2)(2)(2)(3)
Likewise, 70 is divisible by 5 because 70 = (2)(5)(7)
And 112 is divisible by 8 because 112 = (2)(2)(2)(2)(7)
And 630 is divisible by 15 because 630 = (2)(3)(3)(5)(7)
-----ONTO THE QUESTION!---------------------

If n³ is divisible by 24, then we can say that n³= 24k for some positive integer k

Since 24 = (2)(2)(2)(3), we can write: n³= (2)(2)(2)(3)k for some positive integer k

So, what does this tell us about n?
Since there's an 8 hiding in the prime factorization of n³, we can conclude that 8 is a divisor of n³, which means 2 must be a divisor of n
It also tells us that 3 must be a divisor of n
These are the only two guaranteed conclusions we can draw about the divisors of n

If 2 and 3 must be divisors of n, then we can be certain that and is divisible by 6

Answer: C
Intern
Intern
Joined: 30 Aug 2021
Posts: 25
Own Kudos [?]: 10 [0]
Given Kudos: 12
Send PM
Re: If n is an integer and n3 is divisible by 24, what is the la [#permalink]
GreenlightTestPrep wrote:
sandy wrote:
If n is an integer and \(n^3\) is divisible by 24, what is the largest number that must be a factor of n?

(A) 1
(B) 2
(C) 6
(D) 8
(E) 12

-----ASIDE---------------------
A lot of integer property questions can be solved using prime factorization.
For questions involving divisibility, divisors, factors and multiples, we can say:
If N is divisible by k, then k is "hiding" within the prime factorization of N

Consider these examples:
24 is divisible by 3 because 24 = (2)(2)(2)(3)
Likewise, 70 is divisible by 5 because 70 = (2)(5)(7)
And 112 is divisible by 8 because 112 = (2)(2)(2)(2)(7)
And 630 is divisible by 15 because 630 = (2)(3)(3)(5)(7)
-----ONTO THE QUESTION!---------------------

If n³ is divisible by 24, then we can say that n³= 24k for some positive integer k

Since 24 = (2)(2)(2)(3), we can write: n³= (2)(2)(2)(3)k for some positive integer k

So, what does this tell us about n?
Since there's an 8 hiding in the prime factorization of n³, we can conclude that 8 is a divisor of n³, which means 2 must be a divisor of n
It also tells us that 3 must be a divisor of n
These are the only two guaranteed conclusions we can draw about the divisors of n

If 2 and 3 must be divisors of n, then we can be certain that and is divisible by 6

Answer: C



ohhhh i got it now thank you sir
Intern
Intern
Joined: 09 Dec 2020
Posts: 4
Own Kudos [?]: 2 [1]
Given Kudos: 28
Send PM
Re: If n is an integer and n3 is divisible by 24, what is the la [#permalink]
1
I have follow the process below-
n^3/24 so we can say that n^3 must have at least 3 two's and 1 three. As n^3= 2^3 so n=2^1 or 2 and again as n^3= 3 or 3^1, thus n will be 3^3. so the n could be 2X3X3X3= 54. The factors of 54 are- 1, 2, 3, 6, 9, 18, 27 etc. So from the answer choices 6 is the largest one. Is it a correct way?
Intern
Intern
Joined: 27 Jun 2021
Posts: 2
Own Kudos [?]: 1 [1]
Given Kudos: 7
Send PM
Re: If n is an integer and n3 is divisible by 24, what is the la [#permalink]
1
SAHITHI97 wrote:
why 6 but not 12?



N should contain atleast one 2 and one 3.so N Can values [6,12,18,...].if we take 6 or 12 then both options 6 and 12 are correct but if we take N as 18 only 6 is a factor of N but 12 is not.So 6 is the answer.

Posted from my mobile device
User avatar
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 4447
Own Kudos [?]: 68 [0]
Given Kudos: 0
Send PM
Re: If n is an integer and n3 is divisible by 24, what is the la [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep 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.
Prep Club for GRE Bot
[#permalink]
Moderators:
Moderator
1085 posts
GRE Instructor
218 posts

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