Fractions, Decimals, and Percents

Mr. Swaner

A Quick Review

Fractions, decimals, and percents are all parts of a whole. They are also related and can be converted back and forth.

1

4

.25

25%

1

2

.50

50%

0

0

0%

3

4

.75

75%

1

1

100%

Decimals Decimals are like fractions because they also represent

parts of a whole, however, decimals use the base ten system by place value. The place is named by the furthest right number.

tenths, hundredths, thousandths, ten thousandths, hundred thousandths…….

.01234

0.1 is said “one tenth” because the furthest right number is in the tenth place.

0.17 is said “seventeen hundredths” for the same reason,

How would we say 0.015? “fifteen thousandths,”

How would we say 0.83 “Eighty-three hundredths”

Converting decimals to fractions

Converting decimals to fractions is easy because all we have to do is read the decimal and it sounds the same as when we read the fraction.

We read 0.3 as “three tenths.” which is

0.41 is read “forty-one hundredths.”

3

10

41

100

.07

.13

.3

.107

Fractions in base 10

Fractions in base 10 (denominator 10, 100, 1000……..) are easy because they are also read the same way as decimals

3

107

100

Say it and Write it

9

1015

100

Converting Fractions to Decimals If the fraction has a denominator in base ten

(10, 100, 1,000 etc.) It works the same way.

is 0.07 both are read “seven hundredths.”

If the fraction does not have a base ten denominator, you must use long division until you get a repeating or terminating decimal.

7

100

Dividing out a FractionWhen dividing the fraction, it is important to make sure you have the right number “in the house,” or inside the division symbol

3

5

house

basement5 3 house

Dividing out a FractionWhen dividing the fraction, it is important to make sure you have the right number “in the house.” or inside the division symbol

3

5

house

basement5 3 house

5 3 3

5 0.6

Let’s Try a Few

Convert 0.49 to a fraction

Convert .083 to a fraction

Convert to a decimal

Convert to a decimal

Convert to a decimal

73

100

87

1000

3

8

49

100

83

1000

0.73

0.087

8 3

Let’s Try a Few Convert 0.49 to a fraction

Convert .083 to a fraction

Convert to a decimal

Convert to a decimal

73

100

3

8

49

100

83

1000

0.73

8 3

I wish I could do this sometimes during the summer!

These are called terminating decimals A terminating decimal ends

0.26

A Repeating Decimal

Ummmmmm it repeats. Use a bar to show it repeats

0.33333333333333.... 0.3

0.6767676767... 0.67

Day 2?

Warm Up

1) convert 0.16 to a fraction

2) convert to a decimal

3) convert to a decimal

3

10

5

8

Converting Numbers into Percents When you have a fraction with a denominator in base 10 (10, 100, 1,000), numbers can be easily converted into percents.

The word percent literally means per hundred. means you have 40 per hundred or 40%

How could we easily find what percent is?

40

100

7

107

10

10

10

70

100 70%

Converting Decimals to Percents Lucky for us, decimals are ALL in base ten. 0.72 means 72 per hundred or 72%. What happens if we have 0.851 How many hundredths are there? The left over is just a decimal

An easy rule for converting decimals to percents is to simply move the decimal 2 places right.

85

85.1%

Let’s Try Some

0.82 82%

0.258 25.8%

.012 1.2%

Percents to Decimals and Fractions To convert a percent to a decimal, we do the

reverse. Instead of moving the decimal 2 places right, we move it 2 places left and drop the % sign.

56% 56.0% 0.56

Try One on Your Own

27% 27.0% 0.27Convert 27% into a decimal

Now convert 0.27 into a fraction

270.27

100

Closure

How do you convert a decimal to a fraction?

How do you convert a fraction to a decimal?

How do you convert a decimal to a percent?

How do you convert a percent to a decimal?

Write it as it is read

Long divide

Move the decimal right 2 places

Move the decimal left 2 places