The Number Line
4. Adding & Subtracting Integers - B

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.

Negative number, the red arrow moves to the left.

• Now click on Ready for Second Number.

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

Adding a positive number, blue arrow moves to the right.

d. OPERATION: What is the result? What happens if the second number is 'larger' than the first? What happens if it is 'smaller'?

• 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 when two numbers have opposite signs you subtract the 'smaller' from the 'larger' and put the sign of the 'larger' number up front.)

After you click, move the blue slider left and right to see the equation change according to which number is larger!

• Click on Reset to start over.

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LFS with idea for number line by Megan Yanes, idea for pseudo-slider by Zen Biker Maniac and help with "If" statement by Guy Barmoha

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