11-2 Adding Integers
Adding Integers
Course 2
11-2 Adding Integers
We can model what is happening
when we add positive and negative
numbers by using integer chips.
Yellow chips represent positive numbers
= +1
Red chips represent negative numbers.
= -1
Course 2
11-2 Adding Integers
Here is a model using integer chips for 4 + 3:
+
4
+
3
=
7
What observations can we make about our
solution when we add two positive numbers?
Course 2
What do you think our solutions
might be if we add two negative
numbers together?
Sometimes you will see negative
numbers in ( ) and sometimes
you won’t!
11-2 Adding Integers
Adding two negatives together:
Here is a model using integer chips for -4 + -3
+
(-4)
+
(-3)
= (-7)
Try: (-7) + (-5)
What observations can we make about our solutions
when we add two negative numbers together?
Course 2
In Your Notes:
A negative + negative = more
negative! (Just like positive +
positive = more positive!)
Ex: (-2) + (-3) = (-5)
and
2+3=5
11-2 Adding Integers
Now, before we add positive numbers to
negative numbers let’s think about what
happens when we have just +1 and -1
1
+
(-1)
They cancel each other out.
1 + (-1) = 0
(Anything + 0 is always itself!)
Course 2
11-2 Adding Integers
Let’s see an example…
Here is an example with integer chips if we
added 4 + (-3)
+
Cancel each yellow chip for every red chip.
x
x
x
+
x
What do you have left?
So 4 + (-3) = 1
Course 2
x
x
11-2 Adding Integers
You can also think of it this way…
Here is an example with integer chips if we
added 4 + (-3)
+
Simply ask yourself:
“Which do I have more of?”
“How much more?”
So again, 4 + (-3) = 1
Course 2
11-2 Adding Integers
Let’s try this one…
What would 3 + (-5) look like?
+
You can either cancel out yellow/red pairs and
tally what’s left
OR
You can ask yourself:
“Which do I have more of?”
“How much more?”
Course 2
In Your Notes:
When adding a positive # and a
negative # together ask yourself:
1) Which do I have more of ( + or - )
2) How much more? (Subtract them)
Questions?
You have two situations to look out for:
1) Negative + Negative = More Negative
2) Negative + Positive = Ask Your Questions
Let’s Practice
Write the problem and the answer in your notes!
1.
2.
3.
4.
5.
(-5) + 6 1
(-13) + (-6) -19
32 + (-8) 24
(-19) + (-10) -29
12 + (-15) -3
6. (-12) + (-5) -17
7. (-23) + 7 -16
8. (-15) + (-10) -25
9. (-9) + 19 10
10. 12 + (-12) 0