Adding
Integers
Adding Integers
Assume there is a battle going on.
The battle is between the good guys and the bad guys.
If two good guys meet on the battle field, will they join
forces, or will they fight?
Of course, they will join forces to help each other out.
If two bad guys meet on the battle field, will they join
forces, or will they fight?
Of course, they will join forces to help each other out.
If a good guy runs into a bad guy, what will happen?
They will “cancel” each other out.
Adding Integers
• This is an analogy for adding integers
where the yellow army men (the good
guys) represent positive integers, and the
red army men (the bad guys) represent
negative integers.
• If you have two positive integers, and you
add three positive integers, they will join
forces to give five positives
– So: 2 + 3 = 5
Adding Integers
• Similarly, if you have four negatives, and
you add six negatives, they will join forces
to give ten negatives.
– So: -4 + -6 = -10
• However, if you have five negatives, and
you add three positives, they will fight:
Adding Integers
• Any time you have one positive and one
negative, it is called a zero pair
• Why do you suppose that is?
• Because their sum equals ZERO.
• Therefore, you can remove them.
• There are two reds (-2) left.
-5 + 3 = -2

Adding Integers
• Add the following:
9 + -2
-6 + 5
7
-3 + 6
3
-1
Adding Integers
6 + -13
-7
-16 + 5
-15 + -2
-17
-19 + -5
22 + 3
25
64 + -64
-11
-24
0
Adding Integers
1. If the signs are the same….
Add the numbers
Keep the same sign
2. If the signs are different…
Subtract the numbers
Take the sign of whatever you had more
of (+ or –)
The Integer Song
Here is a rule that you must
know when you are adding
integers
If signs are the same
If signs are the same
If signs are the same
Then simply add the numbers
Verse 2
Another rule that you must
know when you are adding
integers
If signs are different
If signs are different
If signs are different
Then just subtract the numbers