Identify the constant. The constant is simply the number in the inequality. For example, if the inequality is x < 6.5, the number is 6.5.
Find its location on the number line. If the number is an integer (whole number), it should be marked. If it is a fraction, you must estimate (or measure with a ruler) to find where it belongs between two numbers. In the example, 6.5 is halfway between 6 and 7.
Place a dot at the constant value in the inequality.
Determine if the inequality requires numbers that are smaller than or greater than this number. If it requires smaller numbers, mark the number line to the left of the dot. If it requires greater numbers, mark to the right. In the example, add a line to the left of the dot.
Add an arrow at the end of your mark, to indicate that the inequality extends indefinitely in that direction.