Number Lines

There are only a few things you need to know about number lines for the SAT.

An example:

Two points on a number line are both 6 units from -2.  What is the distance between them?

A) 0
B) 2
C) 12
D) -8

Strategy:

  1. If you are not given a picture of the number line, draw your own.
  2. Determine if you have an inequality to deal with or not.
  3. Apply the basic rules for determining distance between two points.

Rules about number lines:

  • They continue infinitely in both directions
  • The distance between two points is always the absolute value – it can never be negative
  • An open circle means that number is NOT included
  • A filled-in circle means that number IS included

You may remember this from the inequalities unit, where -1 < x ≤  2.  That would be graphed as: