BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

General Math Strategy

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 28
Joined: Sat Feb 02, 2013 5:45 am

General Math Strategy

by mdecarbo » Wed Apr 03, 2013 11:47 am
Hi all,

Quick question -

Prime numbers - are negative numbers considered Prime (-2, -3, etc.)? Does that make any sense?

Also, I'm in the thick of my identifying weaknesses and practicing those weaknesses part of my prep. Two areas I continue to find difficulty in:
1. Word Problems which involve assigning variables - i stumble over those questions when I see them even though I completely understand how to arrive at an answer. These are questions I believe I should be answering correctly. Any suggestions on how to strengthen this area? I've reviewed the GMAT Prep Now modules over again and did all the GMAT Quant 2nd Edition questions on Word Problems thus far.

2. Data Sufficiency, especially involving arithmetic questions. I find that I either make careless mistakes (i.e. not take in all the rules / limits from question stem (x is positive, x is integer etc.) or I find it difficult to definitely conclude that an equation or question arrives at just one answer. Any suggestions for strengthening DS?

Thanks everyone!
Top
Source: — GMAT Strategy |
User avatar
GMAT Instructor
Posts: 2193
Joined: Mon Feb 22, 2010 6:30 pm
Location: Vermont and Boston, MA
Thanked: 1186 times
Followed by:512 members
GMAT Score:770

by David@VeritasPrep » Wed Apr 03, 2013 1:01 pm
Negative numbers are never prime. Neither is zero or one.

The smallest prime number is two, also the only even prime number.

All other prime numbers are odd and all prime numbers greater than 3 are +/- 1 from a multiple of six. Like 11 and 13 on either side of 12 (a multiple of 6) or 29 and 31 on either side of 30 (a multiple of 6) of course not ever number that is +/- 1 from a multiple of 6 is prime (for example 35 is not prime) but these are the only numbers that can be prime.
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top
User avatar
GMAT Instructor
Posts: 2193
Joined: Mon Feb 22, 2010 6:30 pm
Location: Vermont and Boston, MA
Thanked: 1186 times
Followed by:512 members
GMAT Score:770

by David@VeritasPrep » Wed Apr 03, 2013 1:08 pm
Tips for strengthen Data Sufficiency:

This is something that all students come to at some point. Data Sufficiency is really about being careful and about not making small mistakes or assumptions.

One thing you can do is to make a list of the five number properties (from the Veritas Data Sufficiency book) and keep this with you until they are second nature.

Five Number Properties:

1) Positive / Negative
2) Odd/ Even
3) Non-integers
4) Prime numbers/ factors
5) O and 1

You should make sure that you at least consider these factors for each question. Some are easier to identify - odd/even is usually very easy to spot since they generally say "odd" or "even" in the question. Positive/ Negative, non-integers, and zero and one you should at least consider each time.


Then there is being careful when you do the problems. I have students write a bit more on data sufficiency. I have them do the same thing on each problem. I call this using the "handrails" and this can help you prevent many of the problems that you mention.

Here is an article that details these handrails: https://www.beatthegmat.com/mba/2012/10/ ... -handrails
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Thu Apr 04, 2013 6:13 am
mdecarbo wrote:
2. Data Sufficiency, especially involving arithmetic questions. I find that I either make careless mistakes (i.e. not take in all the rules / limits from question stem (x is positive, x is integer etc.) or I find it difficult to definitely conclude that an equation or question arrives at just one answer. Any suggestions for strengthening DS?
If you're looking for some extra DS resources, we have a free set of videos that cover everything you need to know: https://www.gmatprepnow.com/module/gmat-data-sufficiency

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Post new topic Post Reply
• Page 1 of 1