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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.

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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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