Description: Learn how to plot a simple inequality on a number line. The example used in this video is x < 4. Created by Sal Khan and Monterey Institute for Technology and Education. Now, we want to graph all of the x's that are less than 4, but we're not including 4. And to show that we're not going to include 4, what we're going to do is we're going to draw a circle around 4. And to show that we're going to do all the values less than 4, we want to shade in the number line below 4, going down from 4, just like that.*Teacher Advisor is 100% free.