## Tuesday, February 3, 2009

### PREP FOR GMAT: Number Line

Real numbers can be represented geometrically on a number line, which is considered to extend indefinitely in both directions.

The number zero is at the centre of the number line .

Numbers to the left of 0 on the number line are negative numbers.
Negative numbers are written with a minus sign (e.g., -2).
Numbers to the right of 0 on the number line are positive numbers.
Positive numbers may be written with a plus sign (e.g., +2), but usually we dont (e.g., 5).
Any real number except 0 (zero) is either negative or positive.
Thus, real numbers may be referred to as signed numbers.

On the number line, numbers are ordered with a number to the left is less than a number to the right.

For any two real numbers n and m, three possibilities exist:

n < m (n is less than m)
Point representing n lies to the left of point representing m.
n = m (n equals m)
Point representing n coincides with point representing m.
n > m (n is greater than m)
Point representing n lies to the right of point representing m.