The Number Line
5. Subtracting Negative Numbers

a. SCALE: Set the scale of the number line that is:
• Type in a number >=1 and <=500.
• Then click on the Set Scale button.  

   

Remember: arrow for first number starts from 0, arrow for second number starts from end of first arrow.

• Now click on Ready for First Number.

   

b. FIRST NUMBER: Click and drag the point on the red slider to the value of the first number.

• Now click on Ready for Second Number.

   

c. Second Number: Click and drag the point on the blue slider to the value of the second number.

We are subtracting a negative number, so the arrow shifts direction twice, that is, the blue arrow moves to the right. Does this look like addition of a positive number?

d. OPERATION: What is the result?

• Click on "Show Result " to see it on the number line.

   

e. EQUATION: Write down the equation for the operation and then do the operation. Remember that subtracting a negative number is like adding a positive number.

• Click on Show Equation to check your answer.

   

Move the red slider to a positive number. (Notice the blue slider moves back so we don't go off the number line smile). Now we are adding 2 positive numbers" - easy! Move the red slider to a negative number and say with words how you calculate the result of adding a negative and positive number.

Click on Reset to start over.

   
                    

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     LFS with idea for number line by Megan Yanes and for pseudo-slider by Zen Biker Maniac - Created with GeoGebra