Hi sam0575,

Number Properties are the patterns/rules behind how math "works"; you can spot them by the math "vocabulary words" that are used to describe a given variable (re: odd, even, positive, negative, factor, prime, etc.). All of these questions can be solved by TESTing VALUES; this approach tends to work really well since it takes what seems like a broad concept and grounds it in a real-word example.

For instance, if a question tells you that A, B and C are all ODD INTEGERS and asks about A+B+C, then you can either use what you know about adding up odd integers (the Number Property) or you can TEST VALUES.

Number Property:
Odd + Odd = Even
Even + Odd = Odd

So, Odd + Odd + Odd = Odd

TEST VALUES:
Choose 3 ODD INTEGERS: 1, 3 and 5
1 + 3 + 5 = 9

So, adding up 3 ODD INTEGERS gives us an ODD INTEGER.

Obviously, getting in plenty of reps should help you to improve, but there's another facet to studying that most Test Takers tend to ignore....Just because you got a question right doesn't mean that your approach was the only approach. Revisiting old questions and attempting to solve them in different ways can really help to improve your overall skill set.

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