Subtracting Integers

1
Subtracting Integers
Directions If it says Microsoft Power Point on
the top left of your screen, you are not yet in
the presentation. Click on View and then on
Slide Show. Always wait until instructed and
then click your mouse to go through this
tutorial. To leave it at any time, close by
clicking on the X in the top right corner. If
the is no X or close button, right click and
select End Show. You can then close.
After reading the directions, please click your
mouse.
2
Suggestion Make sure that you are fluent at
adding integers AND that adding integers makes
sense to you, before starting on subtracting
integers. Click now.
3
Consider the addition problem 5 (-3)
The addition tutorial asked us to think of this
as having 5 and then losing 3. You then end up
with 2 in your pocket.
5 (-3) 2
One could have just said 5 3.
Click when ready.
4
All subtraction problems have a
5 3 2 and 5 (-3) 2
related addition problem.
You can use this fact to
do subtraction problems.
Click when ready.
5
Consider 5 9
What addition problem is this related to?
The related addition problem is
5 (-9)
Click when ready.
6
5 9 and 5 (-9)
Both can be thought of as having 5 and then
losing 9. What is the answer to both problems?
5 9 -4 and 5 (-9) -4
You will have a loss of 4, so -4.
See that this makes sense to you before moving
on.
Click when ready.
7
Consider -2 6
What addition problem is this related to?
The related addition problem is
-2 (-6)
When coming up with a related addition
problem, the first number stays the same.
Click when ready.
8
-2 6 and -2 (-6)
Both can be thought of as being down 2 and then
losing 6 more. What is the answer to both
problems?
-2 6 -8 and -2 (-6) -8
You will have a loss of 8, so -8.
Click when ready.
See that this makes sense to you before moving on.
9
Here are the problems that we have done so far.
Study them for a moment.
Subtraction Problem Related
Addition Problem
5 3 2 5 (-3) 2
5 9 -4 5 (-9) -4
-2 6 -8 -2 (-6) -8
Note that, in all of these subtraction problems,
Subtracting a positive number is the same as
the number subtracted is positive.
adding its opposite or negative version.
five minus positive three
Study each subtraction problem and its related
five minus positive nine
addition problem to see that this is true.
Click when ready.
negative two minus positive six
See that this makes sense to you before moving on
to some practice.
10
Here is some practice subtracting positive
numbers.
Please click for your first problem.
If you like, write out the related addition
problem. Or just try doing the calculation in
your head. Click when you have the answer.
-3 7
-10
You are down 3 and then lose 7.
Negative three minus positive seven is -10.
The related addition is -3 (-7).
Click for another problem.
11
Here is some practice subtracting positive
numbers.
Click when you have the answer.
5 11
-6
You are up 5 and then lose 11.
Five minus positive eleven is -6.
The related addition is 5 (-11).
Click for another problem.
12
Here is some practice subtracting positive
numbers.
Click when you have the answer.
4 7
-3
You are up 4 and then lose 7.
Four minus positive seven is -3.
The related addition is 4 (-7).
Click for another problem.
13
Here is some practice subtracting positive
numbers.
Click when you have the answer.
-8 1
-9
You are down 8 and then lose 1.
Negative eight minus positive one is -9.
The related addition is -8 (-1).
The rule Subtracting a number is the same as
adding its opposite. So far the numbers being
subtracted have been positive.
Click when ready.
14
How about 5 (-2) ?
Now we will have the number subtracted be
negative.
State this problem in words.
five minus negative two
Subtracting a negative number ends up being
equivalent to adding its positive version.
Thinking about money no longer makes sense, so we
will simply use this rule.
Click when ready.
15
5 (-2) becomes 5 2
The answer is 7.
Subtracting a negative number is the same
as adding its opposite or positive version.
6 (-8) becomes 6 8 14
-3 (-4) becomes -3 4 1
Click when ready.
16
State this problem in words.
7 - (-2)
Click when ready.
Seven minus negative two
Give the related addition problem.
Click when ready.
7 2
Answer and click.
9
Click to go on.
17
Some people like to see this as putting the two
minuses together to make a plus!
Click to see this happen.
7 ( 2)
Click to go on.
18
State this problem in words.
-8 - (-3)
Click when ready.
negative eight minus negative three
Give the related addition problem.
Click when ready.
-8 3
Answer and click.
-5
Remember that you need to use the addition rules
here. Click to go on.
19
State this problem in words.
5 - (-6)
Click when ready.
five minus negative six
Give the related addition problem.
Click when ready.
5 6
Answer and click.
11
Click to go on.
20
State this problem in words.
-2 - (-9)
Click when ready.
negative two minus negative nine
Give the related addition problem.
Click when ready.
-2 9
Answer and click.
7
Click to go on.
21
In our last practice session there will be both
kinds of problems. Sometimes you will be
subtracting a positive number and sometimes you
will be subtracting a negative number.
Remember Subtracting a number is the same as
adding its opposite.
Click when ready.
22
If you like, write out the related addition
problem. Or just try doing the calculation in
your head. Click when you have the answer.
-2 (-8)
6
Negative two minus negative eight is 6.
The related addition is -2 8.
Click for another problem.
23
Click when you have the answer.
5 12
-7
Five minus positive twelve is -7.
The related addition is 5 (-12).
Click for another problem.
24
Click when you have the answer.
-1 (-4)
3
Negative one minus negative four is 3.
The related addition is -1 4.
Click for another problem.
25
Click when you have the answer.
8 (-2)
10
Eight minus negative eight is 10.
The related addition is 8 2.
Click for another problem.
26
Click when you have the answer.
-6 9
-15
Negative six minus positive nine is -15.
The related addition is -6 (-9).
Click for another problem.
27
Click when you have the answer.
3 7
-4
Three minus positive seven is -4.
The related addition is 3 (-7).
Click for another problem.
28
Here are the problems you just did. Study them a
bit.
Subtraction Problem Related
Addition Problem
-2 (-8) 6
-2 8 6
5 12 -7
5 (-12) -7
-1 (-4) 3
-1 4 3
8 (-2) 10
8 2 10
-6 9 -15
-6 (9) -15
3 7 -4
3 (-7) -4
Again, subtracting a number is the same as
Click when ready.
adding its opposite.
29
Thats it!! Remember to practice. If you
are still confused, try the tutorial again later.
To return, close by clicking on the X in the top
right corner. If the is no X or close button,
right click and select End Show. You can then
close.