gmat preparation courses

It is currently Tue Dec 12, 2017 11:41 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: GRE Number Theory
PostPosted: Thu Sep 13, 2012 4:18 am 
Offline

Joined: Sun May 30, 2010 3:15 am
Posts: 424
Which of the following integers is/are the product of exactly two different prime numbers?
21, 22, 23, 24, 25

Credited Answer(s):
21, 22


The correct answers are 21 and 22. Let's factor each possible answer.
Choice A: 21 = 3 × 7
Choice B: 22 = 2 × 11.
Choice C: 23 = prime number.
Choice D: 24 = 2 × 2 × 3 × 3.
Choice E: 25 = 5 × 5.
Only the first two choices (21 and 22) are the product of exactly two different prime numbers.

----------
23 is also the product of the two following different prime numbers:
23 and 1


Top
 Profile  
 
 Post subject: Re: GRE Number Theory
PostPosted: Thu Sep 13, 2012 4:18 am 
Offline

Joined: Sun May 30, 2010 2:23 am
Posts: 498
Quote:
23 is also the product of the two following different prime numbers:
23 and 1
1 is NOT a prime number.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group