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Adding & Subtracting Integers. Adding Positive Numbers. To understand adding positive and negative numbers we will look at what happens at my ICE CREAM STORE. I have 3 ice cream cones ready. And then I make 4 more…. 4. 3. - PowerPoint PPT Presentation
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Adding & Subtracting Integers
Adding Positive Numbers
I have 3 ice cream cones ready
And then I make 4 more…
I could write this as a number sentence 3 + 4 = 7
To understand adding positive and negative numbers we will look at what happens at my ICE CREAM STORE.
When I have positive numbers (ice cream cones) and I want to find the total amount , I count them together. My total is 7.
3 4
Adding Negative Numbers
First to arrive are these Ice Cream Gobblers.
A few minutes later, more Ice Cream Gobblers arrive.
I could write this as a number sentence -2 + (-3) = -5
Here come the Ice Cream Gobblers. Ice Cream Gobblers take our ice cream cones, so we will represent them with negative numbers.
When I have two groups of negative numbers (Gobblers) and I want to find the total amount, I count them together just as I did with the two groups of positive numbers. My total is -5.
-2 -3
Adding Positive and Negative Numbers
Here are my ice cream cones. A few minutes later, 3 Gobblers arrive.
I could write this as a number sentence 4 + (-3) = 1
This morning in my Ice Cream Store, I have ready 4 ice cream cones.
When I am adding two groups that are different, like my positive cones and my negative Gobblers, I have to watch out. The Gobblers will eat the cones. To find out what happens when I put these groups together I look to see which group is bigger. In this case the cones have a bigger amount (4), than the Gobblers (3). Since the bigger amount is 4 and it is positive my final total will be positive. Three Gobblers will eat 3 of my cones so I will only have one left.
4 -3
Adding Positive and Negative Numbers
Here are my ice cream cones. 4 Gobblers came in.
I could write this as a number sentence 2 + (-4) = -2
Yesterday morning in my Ice Cream Store, I had ready 2 ice cream cones.
To find out what happens when I put these different groups together I look to see which group is bigger. In this case the gobblers have a bigger amount (4), than the cones (2). Since the bigger amount is 4 and it is negative my final total will be negative. Two Gobblers will eat 2 of my cones and 2 Gobblers will be hungry.
2 -4
Practice Adding Signed Numbers
-2 + (-2) =
2 + 1 =
3-4
-5 + (-1) =
-6
-3 + 2 =
-1
-2 + (-3) =
-5
2 + (-1) =
1
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Subtracting Positive Numbers
My friend Jennie came in to visit and knocked 2 of my ice cream cones onto the floor.
I could write this as a number sentence 5 - 2 = 3
Today in my Ice Cream Store, I had ready 5 ice cream cones on the counter.
Since Jennie has ruined them, I will need to subtract them from my inventory.
5
2
Subtracting Negative Numbers
Let’s look at my Gobblers. I have two Gobblers at my counter.
My number sentence starts like this -2 – (-1) = -1
This is the operation where most of the confusion lies. When we subtract negative numbers it is the same as adding.
Subtracting a negative Gobbler, means I’m adding a cone. If I give this cone to one of the Gobblers waiting at the counter. I would only have one Gobbler left.
-2 -1Here comes Gobbler Josh, he doesn’t like vanilla so he’s bringing his ice cream back.
But when we subtract a negative we change the - - to a + -2 +1 = -1
+1
Subtracting Negative Numbers
My number sentence starts like this
-2 1 = -1
When two negatives get together they always change to a positive!
Practice Subtracting Signed Numbers
-2 - (-2) = 2 - 1 = 1
0
-5 - (-1) = -4
-3 - 2 = -5
-2 - (-3) = 1
2 - (-1) = 3
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Practice Adding and Subtracting Signed Numbers
-8 + 5 =
-3 + -2 =
-5-3
-500 - 325 = -825
4 – (- 2 ) =
6
-2 - 7 = -9
400 + (-200) =
200
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Verde Learning Center Adding and Subtracting
Integers Tutorial