Can primes be negative?

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 162
Joined: Thu Mar 18, 2010 5:43 am
Thanked: 6 times
Followed by:1 members

Can primes be negative?

by RumpelThickSkin » Wed Aug 04, 2010 3:12 am
Can somone please clarify for this for please

Junior | Next Rank: 30 Posts
Posts: 23
Joined: Tue Jul 27, 2010 12:26 pm
Location: Washington, DC
GMAT Score:700

by saritalr » Wed Aug 04, 2010 4:16 am
RumpelThickSkin wrote:Can somone please clarify for this for please
According to my prep book: "A prime number is any positive integer larger than 1 with exactly 2 factors: 1 and itself"

A quick google search makes me think that there might be some grey zone at a more advanced theoretical level - but for the GMAT (and for most other purposes), I think the answer is no - primes are positive.

Senior | Next Rank: 100 Posts
Posts: 36
Joined: Thu Dec 31, 2009 5:54 am
Location: New York City
Thanked: 2 times

by bdevas01 » Wed Aug 04, 2010 5:41 am
Nope, primes by definition are positive.

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3380
Joined: Mon Mar 03, 2008 1:20 am
Thanked: 2256 times
Followed by:1535 members
GMAT Score:800

by lunarpower » Fri Aug 06, 2010 3:45 am
doesn't really matter -- you will never have to deal with this issue, one way or the other, on an official problem.
no way.

the problems will almost certainly say something like "positive prime number", making it explicit. if they don't, then there will be some other context that implies or requires the primes in question to be positive.
Ron has been teaching various standardized tests for 20 years.

--

Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi

--

Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.

Yves Saint-Laurent

--

Learn more about ron

User avatar
Master | Next Rank: 500 Posts
Posts: 359
Joined: Wed Mar 11, 2009 4:37 am
Location: Kolkata, India
Thanked: 50 times
Followed by:2 members

by Abhishek009 » Fri Aug 06, 2010 8:16 am
RumpelThickSkin wrote:Can somone please clarify for this for please
Well this link is just for knowledge https://mathforum.org/library/drmath/view/55940.html have a look at this.
Abhishek

Senior | Next Rank: 100 Posts
Posts: 61
Joined: Fri Feb 19, 2010 10:12 am
Thanked: 3 times

by neerajbansal » Sat Aug 07, 2010 6:50 pm
prime has 2 factors...

the number itself and 1


so for a negative number say -7

the factors are

1 -7 and -1 ==> three..

violates the definition of a prime

User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

by sanju09 » Mon Aug 09, 2010 3:40 am
RumpelThickSkin wrote:Can somone please clarify for this for please
Whenever we come across the terminologies like, primes, composites, divisors or factors, etc, they customarily mean positive integers only, with no ambiguity whatsoever. I haven't ever learnt a term like "positive prime number" on real GMAT.
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com

User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

by sanju09 » Mon Aug 09, 2010 4:25 am
RumpelThickSkin wrote:Can somone please clarify for this for please
What is this extra for for?
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com