Last visit was: 21 Nov 2024, 06:04 It is currently 21 Nov 2024, 06:04

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
Verbal Expert
Joined: 18 Apr 2015
Posts: 29998
Own Kudos [?]: 36328 [1]
Given Kudos: 25922
Send PM
Most Helpful Community Reply
Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1111
Own Kudos [?]: 964 [1]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
General Discussion
Retired Moderator
Joined: 09 Jan 2021
Posts: 576
Own Kudos [?]: 846 [1]
Given Kudos: 194
GRE 1: Q167 V156
GPA: 4
WE:Analyst (Investment Banking)
Send PM
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Own Kudos [?]: 12195 [1]
Given Kudos: 136
Send PM
Re: What is the smallest integer that is divisible by 2, 3, 4, 5, 6, 8, an [#permalink]
1
Carcass wrote:
What is the smallest integer that is divisible by 2, 3, 4, 5, 6, 8, and 9?

A) 180
B) 270
C) 360
D) 540
E) 720


One approach is to test each answer choice (starting with the smallest answer choice) to find the smallest value that's divisible by 2, 3, 4, 5, 6, 8, and 9

Another option is to BUILD the number in question. Let's build the number...

-----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!---------------------

Let's say that N = the smallest integer that is divisible by 2, 3, 4, 5, 6, 8, and 9
So if N is divisible by 2, we know that a 2 must be hiding in its prime factorization. That is N = (2)(?)(?)(?)(?)(?)
Likewise, if N is divisible by 3, there must be a 3 hiding in the prime factorization of N. That is N = (2)(3)(?)(?)(?)(?)
Likewise, if N is divisible by 4, there must be two 2's hiding in the prime factorization of N. We already have one 2, so we need to add one more 2 to get: N = (2)(3)(2)(?)(?)(?)
Since N is divisible by 5, we need to add a 5 to get: N = (2)(3)(2)(5)(?)(?)
In order to be divisible by 6, there must be one 2 and one 3 in the prime factorization of N. Since we already have one 2 and one 3, we can be certain that N is already divisible by 6
To be divisible by 8, there must be three 2's hiding in the prime factorization of N. We already have two 2's, so we need to add one more 2 to get: N = (2)(3)(2)(5)(2)(?)(?)
Finally, to be divisible by 9, there must be two 3's hiding in the prime factorization of N. We already have one 3, so we need to add one more 3 to get: N = (2)(3)(2)(5)(2)(3)

So, N = (2)(3)(2)(5)(2)(3) = 360

Answer: C
User avatar
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 5029
Own Kudos [?]: 74 [0]
Given Kudos: 0
Send PM
Re: What is the smallest integer that is divisible by 2, 3, 4, 5, 6, 8, an [#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
Re: What is the smallest integer that is divisible by 2, 3, 4, 5, 6, 8, an [#permalink]
Moderators:
GRE Instructor
83 posts
GRE Forum Moderator
37 posts
Moderator
1111 posts
GRE Instructor
234 posts

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