Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2512:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
Apr 2601:30 AM EDT
-02:30 AM EDT
Learn how Keshav, a Chartered Accountant, scored an impressive 705 on GMAT in just 30 days with GMATWhiz's expert guidance. In this video, he shares preparation tips and strategies that worked for him, including the mock, time management, and more.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
May 0111:00 AM PDT
-12:00 PM PDT
Free- full-length test + 15 concept videos + 150+ short videos + study plan!
05 Apr 2019, 05:43
Kudos
Bookmarks
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
64% (02:28) correct
36%
(02:22)
wrong
based on 189
sessions
History
Date
Time
Result
Not Attempted Yet
The least perfect square, which is divisible by each of 21, 36 and 66 is
A. 213444
B. 214344
C. 214434
D. 231444
E. 231434
A. 213444
B. 214344
C. 214434
D. 231444
E. 231434
05 Apr 2019, 16:25
Kudos
Bookmarks
We need the answer to be divisible by (3)(7), by (2^2)(3^2) and by (2)(3)(11), so it needs to be divisible by 2^2, 3^2, 7 and 11. It also needs to be a perfect square, so it must have even exponents in its prime factorization, and the smallest exponents we could use are 2's for everything, so we just want the value of (2^2)(3^2)(7^2)(11^2).
I'd never want to calculate that, so we can just use some divisibility tests to find the right answer. The answer is divisible by 4, so the last two digits of the right answer must form a multiple of 4. Only answers A, B and D are possible. The answer is also divisible by 9, so the sum of the digits must be a multiple of 9. That leaves only A and B. Finally we can check for divisibility by 7. We can take the wrong answer first: 214,344. To check if this is a multiple of 7, we can just start subtracting large multiples of 7 from it. So we can take away 210,000, leaving us with 4,344. Now we can take away 4200, leaving us with 144. That's not divisible by 7, so 214,344 can't be either. That leaves only answer A, so that must be right.
I'd never want to calculate that, so we can just use some divisibility tests to find the right answer. The answer is divisible by 4, so the last two digits of the right answer must form a multiple of 4. Only answers A, B and D are possible. The answer is also divisible by 9, so the sum of the digits must be a multiple of 9. That leaves only A and B. Finally we can check for divisibility by 7. We can take the wrong answer first: 214,344. To check if this is a multiple of 7, we can just start subtracting large multiples of 7 from it. So we can take away 210,000, leaving us with 4,344. Now we can take away 4200, leaving us with 144. That's not divisible by 7, so 214,344 can't be either. That leaves only answer A, so that must be right.
General Discussion
05 Apr 2019, 05:56
Kudos
Bookmarks
The number has to be divisible by 2,3,7 and 11 in order to be divisible by 21,36 and 66
Since all now are even - all now are divisible by 2
Since sum of all no's is 18 except E which adds to 17, so we can exclude E
Now check divisibility by 7: only A is divisible by 7
Hence answer is A
Posted from my mobile device
Since all now are even - all now are divisible by 2
Since sum of all no's is 18 except E which adds to 17, so we can exclude E
Now check divisibility by 7: only A is divisible by 7
Hence answer is A
Posted from my mobile device
