Where Negative Numbers Come From
Parentheses in the Order of Operations
What You Need to Know About Ranges

How to Add and Subtract on the Number Line

You can use the number line to demonstrate simple addition and subtraction. These first steps in math become a lot more concrete with a visual aid. Here’s the main thing to remember:

  • As you go right, the numbers go up, which is addition (+).

  • As you go left, the numbers go down, which is subtraction (–).

For example, 2 + 3 means you start at 2 and jump up 3 spaces to 5, as illustrated in the below figure.

image0.jpg

As another example, 6 – 4 means start at 6 and jump down 4 spaces to 2. That is, 6 – 4 = 2, as shown in the following figure.

image1.jpg

You can use these simple up and down rules repeatedly to solve a longer string of added and subtracted numbers. For example, 3 + 1 – 2 + 4 – 3 – 2 means 3, up 1, down 2, up 4, down 3, and down 2. In this case, the number line would show you that 3 + 1 – 2 + 4 – 3 – 2 = 1.

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