1. Learn to write decimals and fractions as percents.

2. The students at Westview Middle School are collecting cans of food for the local food bank. Their goal is to collect 2,000 cans in one month. After 10 days, they have 800 cans of food. What percent of their goal have they reached?

3. The model shows that 800 out of 2,000 can be written as , ,
200
400
600
800
1,000
1,200
1,400
1,600
1,800
2,000 2 5 3 5 4 5 1 5 5
0.2
0.4
0.6
0.8
1.0
20%
60%
80%
40%
100%
800
2000 2 5
The model shows that 800 out of 2,000 can be written as , ,
0.4, or 40%. The students have reached 40% of their goal.

4. Additional Example 1: Writing Decimals as Percents
Write 0.7 as a percent.
Method 1: Use pencil and paper. 7 10 70
100
Write the decimal as a fraction with a denominator of 100.
0.7 = =
Write the numerator with a percent sign.
= 70%

5. Additional Example 1 Continued
Write 0.7 as a percent.
Method 2: Use mental math.
Move the decimal point two places to the right and add a percent sign.
0.70 =
70%
= 70%

6. Check It Out: Example 1
Write 0.3 as a percent.
Method 1: Use pencil and paper. 3 10 30
100
Write the decimal as a fraction with a denominator of 100.
0.3 = =
Write the numerator with a percent sign.
= 30%

7. Check It Out: Example 1 Continued
Write 0.93 as a percent.
Method 2: Use mental math.
Move the decimal point two places to the right and add a percent sign.
0.30 =
30%
= 30%

8. Additional Example 2: Writing Fractions as Decimals5 8
Write as a percent.
Method 1: Use pencil and paper. 5 8
= 5 ÷ 8
Use division to write the fraction as a decimal.
= .625
= 62.5%
Write the decimal as a percent.
To divide 5 by 8, use long division and place a decimal point followed by a zero after the 5.
8 5.00
Remember!
.625

9. Additional Example 2 Continued5 8
Write as a percent.
Method 2: Use mental math.
5 ● ● 12.5
Write an equivalent fraction with a denominator of 100. =
Write the numerator with a percent sign.
= 62.5%

10. Check It Out: Example 2 3 5
Write as a percent.
Method 1: Use pencil and paper. 3 5
= 3 ÷ 5
Use division to write the fraction as a decimal.
= 0.60
= 60%
Write the decimal as a percent.

11. Check It Out: Example 2 Continued3 5
Write as a percent.
Method 2: Use mental math.
3 • • 20
Write an equivalent fraction with a denominator of 100. =
Write the numerator with a percent sign.
= 60%

12. Additional Example 3: Ordering Rational Numbers4 4 5
Order 17%, 0.25, , 0.1, , and 20% from least to greatest.
Step 1: Write the numbers as decimals with the
same number of decimal places. 3 4
= 0.75
17% = 0.17
0.25 = 0.25 4 5
= 0.80
0.1 = 0.10
20% = 0.20

13. Additional Example 3 Continued4 4 5
Order 17%, 0.25, , 0.1, , and 20% from least to greatest.
Step 2: Graph the numbers on the number line.
Step 3: Compare the decimals.
0.10 < 0.17 < 0.20 < 0.25 < 0.75 < 0.80
From least to greatest, the numbers are: 0.1, 17%,
20%, 0.25, , . 3 4 5

14. Check It Out: Example 3 1 2 3 4
Order 12%, 0.20, , 0.8, , and 40% from least to greatest.
Step 1: Write the numbers as decimals with the
same number of decimal places. 1 2
= 0.50
12% = 0.20
0.20 = 0.20 3 4
= 0.75
0.8 = 0.80
40% = 0.40

15. Check It Out: Example 3 Continued1 2 3 4
Order 12%, 0.20, , 0.8, , and 40% from least to greatest.
Step 2: Graph the numbers on the number line.
Step 3: Compare the decimals.
0.12 < 0.20 < 0.40 < 0.50 < 0.75 < 0.80
From least to greatest, the numbers are: 12%,
0.20, 40%, , , 0.8. 1 2 3 4

16. Additional Example 4: Choosing a Method of Computation
Decide whether using pencil and paper, mental math, or a calculator is most useful when solving the following problem. Then solve.
If 27 out of 50 people have the newspaper delivered to their home, what percent of these people have the newspaper delivered to their home? 27 50
27 out of 50 =
Think: 27 ÷ 50 divides evenly.
Using pencil and paper is the best method.
= 0.54
= 54%
Write the decimal as a percent.
54% of the people have the newspaper delivered to their home.

17. Check It Out: Example 4
Decide whether using pencil and paper, mental math, or a calculator is most useful when solving the following problem. Then solve.
If 10 out of 50 students have blue backpacks, what percent of the students have blue backpacks? 10 50 20
100 =
Think: The denominator is a multiple of 100.
10 out of 50 =
Mental math or pencil and paper is the best method.
= 0.20
= 20%
Write the decimal as a percent.
20% of the students have blue backpacks.

18. Lesson Quiz
1. Write 0.65 as a percent.
65% 6 10
2. Write as a percent.
60%
Choose the most useful method of computation. Then solve.
3. If 36 out of 80 people surveyed have been on a boat, what percent of these people have been on a boat?
Calculator; 45%