Download Modeling Integers

Adding Integers
Chapter 11-3
Modeling Addition of Integers
 To add integers, you can use counters
or a number line to model integers.
Using Counters
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Color counters represent integers.
Red Counters=negative number
Yellow Counters=positive number
Positive 4=
Negative 3=
How do you think we would model
zero?
ZERO
 Zero is a special number.
 You would use one red & one yellow.
 This is called a zero pair!
 Opposites cancel out—a red and a
yellow erase each other!
You Try!
 Find each sum below using your
counters.
1. 4 + 7 =
11
2. -1 + -5 =
-6
3. -5 + -4 =
-9
Rule: When the signs are the
same…
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What do you do with the numbers?
Add
What will be the sign of your answer?
Keep the same sign
You Try!
 Example:
4 + -7= -3
Find each sum using your counters. Zero Pairs
cancel out! Look carefully at the example!
1. 3 + -4=
-1
2. 1 + -5=
-4
3. 7 + -2 =
5
Rule: When the signs are
different…
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What do you do with the numbers?
Subtract
What will be the sign of your answer?
The sign of the larger number!
Using a number line
 You can use a number line to model
the addition of integers.
 You start at zero facing the positive
direction.
 You move forward for a positive
integer.
 You move backward for a negative
integer.
Example
 Find 3 + (-2) using a number line.
Start at zero. Face the positive
direction. Move forward 3 units for 3.
Then move backward 2 units for -2.
You stop at 1.
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
You Try!
1.) 4 + 2 =
6
2.) -2 + -4 =
-6
3.) 1 + (-5) =
-4
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
You Try!
 Use counters, number line or your
rules to solve the following:
A football team loses 3 yards on one
play. On the next play, the team gains
2 yards. Find the result.
 -3 + 2 = -1
 The result is a loss of 1 yard.