DECIMALS Rounding Decimals Review and Multiplying Decimals.

DECIMALSRounding Decimals Review

andMultiplying Decimals

___ , ___ ___ ___ ___ ___ ___ ___

Th

ou

san

ds

Hu

nd

red

s

Ten

s

On

es

Ten

ths

Hu

nd

red

ths

Th

ou

san

dth

s

Ten

Th

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san

dth

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5 1 8 2 1

Read as 518 and 21 hundredths

Decimals are read as “and” Naming Decimals

Find the number. Circle it.Look next door.4 or less just ignore.5 or more add one more.Example: Round 5368 to nearest hundreds.

Circle the 3 in the hundreds place. Look next door at the 6.

It is 5 or more so add 1 more to the hundreds place.

5368 rounds to 5400

Rounding Review

Round to the nearest tenths

2.876

2.9

Round to the nearest hundredths

31.6999

31.70

Rounding Review

Round to the nearest tenths

3.478

3.5

Round to the nearest hundredths

22.5972

22.60

Rounding Review

Steps for Multiplying Decimals

Step 1: Write the problem vertically.Step 2: Ignore the decimal point(s) and multiply.

Step 3: Determine where the decimal point goes in the product.

Place the decimal point in the answer by counting how many places the decimal point has moved.

Multiplying Decimals

Multiply 3 x 0.14

0.14 3 x 0.14

=

0.42


Multiply 3 x 0.14

2

Step 1: Write the problem vertically 0.14

x 3 Step 2: Ignore the decimal points and multiply


The decimal moves two places to the left

1

40

0.42


Multiply 5 x 0.18

0.18 5 x 0.18

=

0.90


1whole 1whole1whole

Multiply 5 x 0.18

0


x 5 Step 2: Ignore the decimal points and multiply



4

90

0.90


Multiply 0.2 x 0.6

0.2 0.6

=

0.2


Multiply 0.2 x 0.6

0.2 0.6

=

0.2 x 0.6


Multiply 0.2 x 0.6

0.2 0.6

=

0.2 x 0.6= 0.12


Multiply 0.2 x 0.6

2


x 0.6 Step 2: Ignore the decimal points and multiply



10

0. 12


Multiply 0.4 x 0.7

0.4 0.7

=

0.4


Multiply 0.4 x 0.7

0.4 0.7

=

0.4 x 0.7


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Multiply 0.4 x 0.7

0.4 0.7

=

0.28


Multiply 0.4 x 0.7

8


x 0.7 Step 2: Ignore the decimal points and multiply



20

0. 28


Multiplying Decimals200

x .250+

50000

001004

Move the decimal two places

to the left in your answer.

.

Multiplying DecimalsHOW MANY DECIMAL PLACES?

1 decimal place3.1

2) (0.4)(2.53)0.4

2.53

1) 3.1(0.28)

1.012

0.28 2 decimal places0.868 1 + 2 = 3 decimal

places1 decimal place2 decimal places1 + 2 = 3 decimal places

Multiplying Decimals1) 0.16

x 30000084084

12) 70

x 1.2041007048

+

3)

1

0.0048 x 32

690044635

1

1

1

2

0

0

1

0

Evaluate The PowerAn exponent tells how many

times a number is multiplied by itself.

34

BaseExponent

3 is written as 3 • 3 • 3 • 3 = 81 4

This exponent is read three to the fourth power.

Evaluate The PowerEvaluate (0.2)2

4

This means (0.2)(0.2) 0.2

x 0.2

The decimal goes moves two places to the left

00

0. 04

Calculate Area With Decimals

4 in.

0.58 in.

Area = base x height

Multiply 4 x 0.58

2

0.58

x 4

The decimal moves two places to the left.

3

32

2.32 in2

2

Area is square

units!

Review

Multiply 0.4 x 0.14

6


x 0.4Step 2: Ignore the decimal points and multiply


The decimal moves 3 places to the left.

1

50

0.056

Multiplying Decimals#5

0

Evaluate (0.5)2

5

This means (0.5)(0.5) 0.5

x 0.5The decimal moves two

places to the left.

20

0. 25

#6

2

2 in.

0.98 in Area = base x height

# 7

Multiply 2 x 0.98

6

0.98x 2

The decimal moves two places to the left.

1

91

1.96 in2

1

Area is square

units!

The Area (A) is the number of square units needed to cover a figure.

DECIMALS Rounding Decimals Review and Multiplying Decimals.

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