Lesson Objectives
  • Demonstrate the ability to construct a number line for the whole numbers
  • Learn how to add two whole numbers using a number line
  • Learn how to add more than two whole numbers using a number line

How to Add Whole Numbers using a Number Line


At this point, you should be fairly comfortable with creating a number line that represents the whole numbers. Recall the whole numbers start with 0 and increase in increments of 1 indefinitely.
Whole Numbers: {0,1,2,3,4,5,...} Number Line for the Whole Numbers You should also be fairly comfortable with single digit addition. This process can be visualized using a number line to count. Using a number line to perform addition may seem trivial right now, but this method will help enormously when we get to adding and subtracting integers.

Adding two Numbers on a Number Line

  • Start on the number line at the left most number of the addition problem
  • Move to the right by the number of units being added
Example 1: Add 3 + 4, using the number line Adding 3 + 4 using a number line
  • Start out at the number 3, the left most number of the addition problem
  • Move to the right by 4 units
  • We end up at 7, which is our answer
  • 3 + 4 = 7
Example 2: Add 4 + 14, using the number line Adding 4 + 14 using a number line
  • Start out at the number 4, the left most number of the addition problem
  • Move to the right by 14 units
  • We end up at 18, which is our answer
  • 4 + 14 = 18

Adding more than two Numbers on a Number Line

  • Start on the number line at the left most number of the addition problem
  • Move to the right by each number of units being added
Example 3: Add 5 + 3 + 5, using the number line Adding 3 + 4 using a number line
  • Start out at the number 5, the left most number of the addition problem
  • Move to the right by 3 units
  • We end up at 8
  • Move to the right by 5 units
  • We end up at 13, which is our answer
  • 5 + 3 + 5 = 13