Multiplying Decimals NS3
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Multiplying Decimals NS3 I can multiply decimals.
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Multiply Decimals Step 1 --- Ignore the decimal Step 2 --- Rewrite the problem Step 3 --- Multiply the problem Step 4 --- Count the decimal places Step 5 --- Move decimal that many places in your answer
Transcript of Multiplying Decimals NS3
Multiplying DecimalsNS3
I can multiply decimals.
Multiply Decimals
Step 1 --- Ignore the decimal Step 2 --- Rewrite the problem Step 3 --- Multiply the problem Step 4 --- Count the decimal places Step 5 --- Move decimal that many places in
your answer
Guided Practice
4 . 5 6X 0 . 3 9
NOTE BOOK
You can use graph paper to model decimal multiplication. Here is a model of the product of 0.7 and 0.3.
1
1
0.3
0.7
Because 21 of the 100 squares are shaded, 0.7 0.3 = 0.21
Words
Numbers
Multiplying Decimals
Multiply decimals as you would whole numbers. Then place the decimal point in the product. The number of decimal places in the product is equal to the sum of the number of decimal places in the factors.
0.7 0.3 = 0.21
Multiplying Decimals
EXAMPLE 1 Multiplying Decimals
5.820.41
2 decimal places
2 decimal places
5 8 22 3 2 80
4 decimal places
–––+––––––
2.3 8 6 2–––––––
1234
Example: 5.63 x 3.7
5.633.7x
6.45
18
2 decimal places
0 decimal places
51606450
––––––116.10
Because 6 20 = 120, the product is reasonable.
EXAMPLE 2 Multiplying Decimals
–––+––––––
After you place the decimal point, you can drop any zeros at the end of an answer.
2 decimal places
CHECK
ANSWER 6.45 18 = 116.1
Write a zero before the 7 as a placeholder so that the number has 5 decimal places.
6.45
18
2 decimal places
0 decimal places
5160645
––––––116.10
Because 6 20 = 120, the product is reasonable.
1.273
0.06
3 decimal places
2 decimal places
76380.0 5 decimal places
Because 1 0.06 = 0.06, the product is reasonable.
EXAMPLE 2 Multiplying Decimals
–––+–––––– ––––––– –––+
After you place the decimal point, you can drop any zeros at the end of an answer.
2 decimal places
CHECK CHECK
Multiplying Decimals
ANSWER 6.45 18 = 116.1 ANSWER 1.273 0.06 = 0.07638
Central Park Central Park is a rectangular park about 2.5 miles long and about 0.5 mile wide. What is the area of Central Park?
EXAMPLE 3 Multiplying Decimals to Find Area
SOLUTION
= l w2.5(0.5)
A = l w
Substitute 2.5 for l and 0.5 for w.
= 1.25
Write formula for area of a rectangle.
ANSWER The area of Central Park is about 1.25 square miles.
Multiply.
Showdown!!!!1. .31 x .7 =
.217
2. .9 x .03 = .027
3. 2 x .006 = .012
4. .66 x 2.52 = 1.6632
