copyright©amberpasillas2010
copyright©amberpasillas2010
For Learning to Happen!
•Take out a piece of paper.•Take out something to write with.•Try all of the examples.•Ignore all other distractions.•Watch the 1st slide then I will have you try a few examples.
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1 • 1 = +1 1 • -1 = -1 -1 • -1 = +1
-1 • -1 • -1 = -1
Odd # of Negatives = Negative
Even # of Negatives = Positive
-1 • -1 • -1 • -1 = +1
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1) 0.16x 30
00008+ 4084
12) 70
x 1.2041007048
+
3)
1
0.0048 x 32
690044635
1
1
1
2
0
0
1
+ 0
Try these on your paper!
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Multiply (-3) (-0.14)
2
Step 1: Write the problem vertically 0.14
x 3Step 2: Ignore the decimal points and multiply Step 3: Determine where the decimal point goes in the product.
1
40
0.42
– . – = +
Step 4: Determine the sign of your answer using your integer rules.
The answer is POSITIVE
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Multiply (-0.4) (0.6)
4
0.4
x 0.6
The decimal moves two places to the left
20
– 0. 24
Signs are the
sameSigns are
different
POSITIVE
NEGATIVE
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Multiply (0.8) (-0.9)
2
0.8
x 0.9
The decimal moves two places to the left
70
– 0. 72
Signs are the
sameSigns are
different
POSITIVE
NEGATIVE
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HOW MANY DECIMAL PLACES?
1 decimal place3.0
2) (-0.40)(-2.0)0.40 2.0
1) -3.0(0.20)
0.800
0.20 2 decimal places0.600 1 + 2 = 3 decimal
places
2 decimal place1 decimal places2 + 1 = 3 decimal places
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3.0
2) (-0.40)(-2.0)0.40 2.0
1) -3.0(0.20)
0.800
0.200.600
WHAT IS THE SIGN OF YOUR ANSWER?
NEGATIVE
POSITIVE
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Find the product.
(-2.8)(-3)
-2.8 -3
8.4 POSITIVE
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Divide 0.27 -3
3 0 .27.0
0 02 7
9
27 0
Step 2: Move the decimal point in the dividend straight up into the quotientStep 3: Divide as usual.
Step 1: Write the problem in the long division format. Ignore the negatives.
TRICK: Dead Monkeys Smell Bad!
= -0.09
Step 4: Determine the sign.
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Divide -0.65 5
5 0 .65.1
0 51 5
3
15 0
Step 2: Move the decimal point in the dividend straight up into the quotientStep 3: Divide as usual.
Step 1: Write the problem in the long division format. Ignore the negatives.
TRICK: Dead Monkeys Smell Bad!
= -0.13
Step 4: Determine the sign.
copyright©amberpasillas2010
copyright©amberpasillas2010
Multiply Negative DecimalsMultiply (-0.3) (0.9)
7
0.3
x 0.9
The decimal moves two places to the left.
20
– 0. 27
#10
Signs are the same
Signs are
different
POSITIVE
NEGATIVE
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Divide Negative Decimals
Divide (- 0.75) (0.15)
015 0 75. 0
0 075
5
75 0
. .. .
#11
+ + = + – – = +
+ – = –– + = –
Signs are the same
Signs are different
POSITIVE
NEGATIVE
= – 5
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Extras
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0-2.0 -1.5 -1.0 -0.5 1.5 0.5
1.0 2.0
Negative Positive
-1
0.5
> -2
< 1.5
#
<Less than
>Greater than
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+ + = +– – = +
+ – = –– + = –
Signs are the same
Signs are
different
POSITIVE
NEGATIVE
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