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

It is currently 17 Jul 2018, 12:35

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 units digit of the product of the first 50 primes?

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

Hide Tags

1 KUDOS received
Intern
Intern
avatar
Joined: 04 Mar 2010
Posts: 9
Reviews Badge
What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 06 Jan 2015, 23:09
1
2
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

81% (00:20) correct 19% (01:05) wrong based on 129 sessions

HideShow timer Statistics

What is the units digit of the product of the first 50 primes?

A. 0
B. 1
C. 3
D. 5
E. 9
Most Helpful Community Reply
3 KUDOS received
Intern
Intern
avatar
Joined: 10 Feb 2013
Posts: 14
Location: India
Concentration: General Management, Finance
GMAT Date: 05-16-2015
GPA: 3.67
WE: Programming (Computer Software)
Re: What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 07 Jan 2015, 00:08
3
2
2and 5 r thr in the prime list list so product is 0 ..so no matter how many primes u consider (>3) the units digit is always "0"


reddyMBA wrote:
Just wanted to share - I felt, its kind of easy but tricky.

Q.) What is the units digit of the product of the first 50 primes?

A.) 0
B.) 1
C.) 3
D.) 5
E.) 9

Please give me Kudo's if you like it.
General Discussion
1 KUDOS received
SVP
SVP
User avatar
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1837
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 07 Jan 2015, 02:23
1
2
Answer = A.) 0

Just write down the first 4 prime numbers & we get the answer

1*2*3*5 ............ and so on... will end up with 0 in units place

Similar question......

What is the units digit of the product of the first 100 even numbers?

2*4*6*8*10 ............. will end up in 0 in the units place

What is the units digit of the product of the first 100 odd numbers?

1*3*5*7 ................... will end up in 5 in the units place

Experts: Are these potential GMAT questions.... ??
_________________

Kindly press "+1 Kudos" to appreciate :)

Director
Director
User avatar
Joined: 07 Aug 2011
Posts: 561
Concentration: International Business, Technology
GMAT 1: 630 Q49 V27
GMAT ToolKit User
Re: What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 01 Feb 2015, 01:17
PareshGmat wrote:
Answer = A.) 0

Just write down the first 4 prime numbers & we get the answer

1*2*3*5 ............ and so on... will end up with 0 in units place

Similar question......

What is the units digit of the product of the first 100 even numbers?

2*4*6*8*10 ............. will end up in 0 in the units place

What is the units digit of the product of the first 100 odd numbers?

1*3*5*7 ................... will end up in 5 in the units place

Experts: Are these potential GMAT questions.... ??


Prime starts from 2 not from 1 .. . . .
_________________

Thanks,
Lucky

_______________________________________________________
Kindly press the Image to appreciate my post !! :-)

Expert Post
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11979
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 01 Feb 2015, 16:36
Hi All,

On Test Day, sometimes the biggest clue/shortcut will be in how the answer choices are written.

We're asked to think about the PRODUCT of the first 50 prime numbers. We clearly are NOT expected to do all of that math, so there MUST be a pattern that we can use to get to the correct answer.

Since the first prime is "2", the product of all of those primes MUST be EVEN. Considering how THESE answers are written, only one answer matches...

Final Answer:

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Director
Director
User avatar
G
Joined: 23 Jan 2013
Posts: 598
Schools: Cambridge'16
Re: What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 25 Dec 2016, 01:28
no need to count. All primes are odd and multiplying by 2 (only even prime) we get even

Only A fits
Senior Manager
Senior Manager
User avatar
S
Joined: 25 Mar 2013
Posts: 265
Location: United States
Concentration: Entrepreneurship, Marketing
GPA: 3.5
GMAT ToolKit User Reviews Badge
Re: What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 05 Jan 2017, 09:29
Product of 50 primes
2 , 3 , 5 , 7 ...
2x5 = 10
A
_________________

I welcome analysis on my posts and kudo +1 if helpful. It helps me to improve my craft.Thank you

Director
Director
avatar
G
Joined: 02 Sep 2016
Posts: 742
Premium Member
Re: What is the units digit of the product of the first 50 primes? [#permalink]

Show Tags

New post 03 Apr 2017, 23:21
That can be one way to solve: 2*5=10
So no matter what the other nos. are the answer will end with 0 at unit's place.

I solved it using the power of even numbers.

Even is there is one even no. in the list, then the product will be even and luckily 2 is part of the list.
Only even choice is 0.
_________________

Help me make my explanation better by providing a logical feedback.

If you liked the post, HIT KUDOS !!

Don't quit.............Do it.

Re: What is the units digit of the product of the first 50 primes?   [#permalink] 03 Apr 2017, 23:21
Display posts from previous: Sort by

What is the units digit of the product of the first 50 primes?

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

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.