Decimals, Fractions, andPercent Review

Converting Fractions to Decimals

• To convert a fraction to a decimal, divide the numerator by the denominator. You will get a decimal that terminates or repeats. If it repeats, place a bar (--- ) over the first number

that repeats. Example 1: Convert 3/4 to a decimal

3/4 = 3÷4= 0.75

( terminating decimal) Example 2: Convert 2/3 to a decimal

2/3= 2÷3= 0.66 ( repeating decimal )

Converting Decimals to Percents

• In order to convert a decimal to a percent, either multiply the decimal by 100 and write the percent sign (%), or move the decimal point two places to the right and write the percent sign (%).

Example 1: Convert 0.20 to a percent0.20x 100= 20% or 0.20= 0. 2 0= 20%Example 2: Convert 4.00 to a percent4x 100=400% or 4.00= 4. 0 0=400%

Converting Percents to Decimals

• When converting a percent to a decimal, either divide the percent by 100 and put the decimal point, or move the decimal point two places to the left and put the decimal point.

Example 1: Convert 72% to a decimal72%= 72÷ 100= 0.72 or 7 2 . 0= 0.72Example 2: Convert 62.5% to a decimal62.5%= 62.5÷ 100= 0.625 or 6 2 . 5= 0.625

Copy and complete this chartPercentage Decimal Decimal Percentage

1. 27% .27 7. 0.87 87%

2. 2% .02 8. 0.08 8%

3. 55% .55 9. 0.42 42%

4. 5% .05 10. 0.04 4%

5. 17% .17 11. 0.71 71%

6. 98% .98 12. 0.07 7%

Converting Fractions to Percents

• To convert a fraction to a percent, change the fraction to a decimal ( by dividing the numerator by the denominator ). Then multiply the decimal by 100 and put a percent sign (%). Another way is to move the decimal point two places to the right and put a percent sign (%).

Example 1: Convert 1/2 to a percent1/2= 1÷ 2 = 0.50 0.50x 100= 50.00=50% or 0.50= 0. 5 0= 50%Example 2: Convert 1/3 to a percent1/3= 1÷3= 0.3330.333x 100= 33.300=33.3% or 0.333=0. 3 3 3=33.3%

Another way to Convert Fractions to Percents

• Make a proportion by putting a 100 under the percent. Then use cross products or mental math. Then add a percent sign.

Example 1: Convert 1/5 to a percent

Multiply the top and the bottom by 20 so x = 20%

Example 2: Convert 3/25 to a percent

Multiply the top and the bottom by 4 so x = 12%

1005

1 x

10025

3 x

Try these:

1. Work out your percentage if you got 12 out of 25

2. Work out your percentage if you got 15 out of 25

3. Work out your percentage if you got 17 out of 20

4. A player scores 4 times out of 10 shots. What percentage did they make?

5. Calculate the score percentage if out of 15 shots 12 are successful

48%

60%

85%

40%

80%

Percent of Increase

and Decrease

A percent change is an increase or decrease given as a percent of the original amount. Percent increase describes an amount that has grown and percent decrease describes an amount that has be reduced.

From $10 to $155

10 = 0.50

New Amount -OriOrig

ginal%Chainal Am

ngeount

%

% increase50%

The original cost of a CD was $10. The same CD now costs $15. It increased $5.

Change decimal to a percent

Percent of Decrease

From $12 to $9

312 =

Change in PrOrigi

ice% Cha

nal Am tnge

oun

%

% decrease25%

The original cost of a basketball was $12. The same basketball now costs $9. It decreased $3.

Change decimal to a

%

0.25

Finding Percent Increase and Decrease

Find each percent change. Tell whether it is a percent increase or decrease.

Movie tickets went from $8 to $10

= 0.25

= 25% Write the answer as a percent.

Simplify the numerator.Simplify the fraction.

$8 to $10 is an increase, so a change from 8 to 10 is a 25% increase.

Shoes went from $75 to $30

= 0.6

= 60%Write the answer as a percent.

Simplify the numerator.Simplify the fraction.

75 to 30 is a decrease, so a change from 75 to 30 is a 60% decrease.

Finding Percent Increase and Decrease

Find the percent change. Tell whether it is a percent increase or decrease.

Practice:Worksheet