Download Add, Subtract, Multiply, and Divide Decimals

Add, Subtract, Multiply,
and Divide Decimals
SWBAT add and subtract positive and negative
decimals; multiply positive and negative
decimals; divide positive and negative decimals
Add and Subtract Decimals
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How do you add and subtract positive and
negative integers?
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4 + 7 = 11
-4 + -7 = -11
-4 + 7 = 3
What is the most important thing to remember
when adding and subtracting decimals?
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You MUST align the decimal points!!!
Examples
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410.3 + (-18.01)
-17.6 – 2.98
0.44 – 0.87
-2.4 – (-5.6)
-3.992 + 7.08
Try the problems on your paper
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15.0458
-1.3
-13.1
8.87
7.9091
-4.1123
Multiplying Decimals
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What sign does your answer have when you multiply
the following:
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Positive x Positive = Positive
Negative x Negative = Positive
Negative x Positive = Negative
How do you determine how many decimal places
should go in your answer when multiplying two
decimals?
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Count the decimal places of the numbers you are
multiplying, your answer should have the same number.
Examples
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0.0375(-2)
(-5.01)(3)
(0.205)(-2)
-6.15(0.45)
3.2(0.2 + 0.5)
Try the problems on your paper
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0.0338
0.04
-2.259
20.5
7.2
Dividing Decimals
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What sign does your answer have when you divide
the following:
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Positive x Positive = Positive
Negative x Negative = Positive
Negative x Positive = Negative
How do you determine where the decimal should go
in your answer when dividing decimals?
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It goes directly above the decimal in the dividend. If there
is a decimal in the divisor, move it to make a whole
number and then move the decimal the same number of
places in the dividend.
Examples
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31.62 ÷ -9.57
-46.332 ÷ - 836.4
-0.075 ÷ 0.23
6.19 ÷ 35
Try the problems on your paper
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12.45
-0.025
170