NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 01:02 It is currently 24 Apr 2024, 01:02
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

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

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
avatar
reddyMBA
Intern
Intern
Joined: 04 Mar 2010
Posts: 6
Own Kudos [?]: 29 [11]
Given Kudos: 1
Send PM
Reviews Badge
What is the units digit of the product of the first 50 primes? [#permalink] New post   06 Jan 2015, 23:09
1
Kudos
10
Bookmarks
00:00
A
B
C
D
E

Difficulty:

5% (low)

Question Stats:

85% (00:43) correct 15% (01:23) wrong based on 191 sessions
Hide Show 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
ShowHide Answer
Official Answer
A
Most Helpful Reply
avatar
jayanth7290
Intern
Intern
Joined: 10 Feb 2013
Posts: 14
Own Kudos [?]: 24 [6]
Given Kudos: 6
Location: India
Concentration: General Management, Finance
GMAT Date: 05-16-2015
GPA: 3.67
WE:Programming (Computer Software)
Send PM
Re: What is the units digit of the product of the first 50 primes? [#permalink] New post   07 Jan 2015, 00:08
4
Kudos
2
Bookmarks
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
avatar
PareshGmat
SVP
SVP
Joined: 27 Dec 2012
Status:The Best Or Nothing
Posts: 1562
Own Kudos [?]: 7207 [4]
Given Kudos: 193
Location: India
Concentration: General Management, Technology
WE:Information Technology (Computer Software)
Send PM
Re: What is the units digit of the product of the first 50 primes? [#permalink] New post   07 Jan 2015, 02:23
1
Kudos
3
Bookmarks
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.... ??
User avatar
Lucky2783
Senior Manager
Senior Manager
Joined: 07 Aug 2011
Posts: 425
Own Kudos [?]: 1751 [0]
Given Kudos: 75
Concentration: International Business, Technology
GMAT 1: 630 Q49 V27
Send PM
GMAT ToolKit User
Re: What is the units digit of the product of the first 50 primes? [#permalink] 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 .. . . .
User avatar
L
EMPOWERgmatRichC
GMAT Club Legend
GMAT Club Legend
Joined: 19 Dec 2014
Status:GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Posts: 21846
Own Kudos [?]: 11664 [2]
Given Kudos: 450
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Send PM
Re: What is the units digit of the product of the first 50 primes? [#permalink] New post   01 Feb 2015, 16:36
2
Kudos
Expert Reply
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:
Show Spoiler
A


GMAT assassins aren't born, they're made,
Rich
User avatar
G
Temurkhon
Senior Manager
Senior Manager
Joined: 23 Jan 2013
Posts: 429
Own Kudos [?]: 263 [0]
Given Kudos: 43
Schools: Cambridge'16
Re: What is the units digit of the product of the first 50 primes? [#permalink] 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
User avatar
S
kanusha
Manager
Manager
Joined: 25 Mar 2013
Posts: 166
Own Kudos [?]: 130 [0]
Given Kudos: 101
Location: United States
Concentration: Entrepreneurship, Marketing
Schools: Yale '17 HBS '17 Stanford '17
GPA: 3.5
Send PM
GMAT ToolKit User Reviews Badge
Re: What is the units digit of the product of the first 50 primes? [#permalink] New post   05 Jan 2017, 09:29
Product of 50 primes
2 , 3 , 5 , 7 ...
2x5 = 10
A
avatar
G
Shiv2016
Director
Director
Joined: 02 Sep 2016
Posts: 528
Own Kudos [?]: 194 [0]
Given Kudos: 275
Re: What is the units digit of the product of the first 50 primes? [#permalink] 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.
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 32639
Own Kudos [?]: 821 [0]
Given Kudos: 0
Send PM
Re: What is the units digit of the product of the first 50 primes? [#permalink] New post   14 Oct 2021, 12:44
Hello from the GMAT Club BumpBot!

Thanks to another GMAT 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.
GMAT Club Bot
gmatclubot
Re: What is the units digit of the product of the first 50 primes? [#permalink]
14 Oct 2021, 12:44
Moderators:
Bunuel
Math Expert
92888 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions