2. Subtracting Integers

3. Subtracting Integers Let’s model integer subtraction. 4 – 2 -5 – -2 2
4 – – -2 2 -3

4. Subtracting Integers How are we going to do this?
We have to have three negatives to take away. How can we get them?
5 – -3
Add three zero pairs
Do we still have 5?
5 – -3 = 8
YES!
Now take away -3.

5. Subtracting Integers
Do these:
6 – -5
= 11
-8 - 2
= -10

6. Subtracting Integers Go back to our battle example.
What is happening in these examples?
-8 – 2 = -10
6 – -5 =11
What is really happening is that I am adding the opposite each time.
What is ?
-10
What is 6 + 5? 11

7. Subtracting Integers
So, using the battle analogy, here is how we remember how to subtract.
We are going to fire the cannon twice.
What sound will that make?
Boom!
The first blast will change our subtraction sign to an addition sign.
The second will change the second number to its opposite.

8. Subtracting Integers Let’s try one. -9 – 4 8 – 2 -9 + -4 8 + -2 = -13
8 – 2
8 + -2
= 6
12 – -5
= 17
-9 – 4
= -13
-15 – -12
= -3

9. Integers Song
Verse 3
Here is a rule that you must know when you’re subtracting integers
Add the opposite number
Then follow the addition rule