Name
Chapter 23, Lesson 1
Reteach
Date
Hands On: Model Percent
CA Standards
NS 1.2, MR 2.3
The word percent means “per hundred.” A percent compares a
number to 100.
Write the percent of the grid that is shaded. Then write a decimal and
a fraction in simplest form for the shaded part.
Step 1 Count the number of shaded
squares and write the percent. 48 out of 100
squares are shaded. 48% is shaded.
Step 2 Write the percent as a decimal
and as a fraction in simplest form.
48% = 0.48
48
48% = 48 out of 100 = ___
100
12
48 ÷ 4
______
= __
25
100 ÷ 4
1.
2.
3.
Complete the table. Write each fraction in simplest form.
4.
Fraction Form
Decimal Form
37
___
100
0.37
5.
0.82
Percent
82%
Writing Math Use grids to show 3% and 30%. How can you
tell which percent is greater? Explain.
Reteach
Copyright © Houghton Mifflin Company. All rights reserved.
23–20
Use with text pages 500–501.
Name
Chapter 23, Lesson 2
Reteach
Date
Relate Percents to Fractions
and Decimals
CA Standards
NS 1.2, MR 2.3
15
A fraction like ___
can be written as a percent by using equivalent
25
fractions or by using division.
Way 1
Way 2
Use equivalent fractions.
15
Step 1 Multiply to write __
as a fraction
25
with a denominator of 100.
Use division.
Step 1 Divide 15 by 25 to find the
decimal equivalent of the fraction.
15
__
= 15 ÷ 25 = 0.6
25
Think: 25 times what number equals 100?
×4
15
= 60
25
100
×4
Step 2
60
Write ___
as a percent.
100
Step 2
60
___
= 60%
100
Write 0.6 as a percent.
0.6 = 0.60 = 60%
15
= 60%.
Solution: __
25
Find the percent by finding an equivalent fraction or dividing the
numerator by the denominator.
1
1. __
11
2. ___
3
3. __
33
4. ___
9
5. ___
1
6. __
7
7. ___
3
8. ___
2
25
20
4
9. __
5
8
4
3
10. __
4
20
2
11. __
5
50
25
19
12. ___
20
Writing Math Is it always possible to use equivalent fractions
as a way to write a fraction as a percent? Explain.
Reteach
Copyright © Houghton Mifflin Company. All rights reserved.
23–26
Use with text pages 502–504.
Name
Chapter 23, Lesson 3
Reteach
Date
Compare and Order Fractions
Decimals, and Percents
CA Standard
NS 1.1
1.
Compare 42%, 0.65, and _
4
Way 1
Compare using a number line.
1
4
0.65
42%
1
0
Way 2
Write each number as a decimal.
Step 1 Write the fractions
as a decimal by dividing.
Step 2 Think of the
percent as a number of
hundredths.
Step 3 Compare the
decimals.
42 = 0.42
42% = ___
100
_1_ = 1 ÷ 4 = 0.25
4
0.25 < 0.42 < 0.65
Which is greatest?
1.
23%
9
___
50
0.25
11
2. ___
20
79%
0.5
Which is least?
3.
0.85%
97%
23
___
25
4.
30%
0.38
1
__
5
Writing Math Why is it best to write percents and fractions as
decimals when comparing them?
Reteach
Copyright © Houghton Mifflin Company. All rights reserved.
23–32
Use with text pages 506–507.
Name
Chapter 23, Lesson 4
Reteach
Date
Percent of a Number
CA Standards
NS 1.2, MR 3.2
Different Ways to find 10% of 30
Way 1
Way 2
Step 1 Write the percent as a fraction in
simplest form.
Step 1
Step 2
10
1
10% = ___
= __
100
10
10% = 10 hundredths = 0.10 = 0.1
Step 2
Multiply.
Write the percent in decimal form.
30
1 × 30 = __
1 × __
__
10
10
1
30
__
= 10
Multiply.
0.10
× 30
____
3.00
=3
30 × 0.10 = 3
Solution: 10% of 30 is 3.
Solve by writing the percent as a fraction.
1.
70% of 70 = n
2.
65% of 20 = n
3.
45% of 40 = n
4.
15% of 60 = n
7.
16% of 10 = n
8.
28% of 50 = n
Solve by writing the percent as a decimal.
5.
30% of 90 = n
6.
50% of 70 = n
Writing Math Which way do you think is easier to find the
percent of a number? Explain.
Reteach
Copyright © Houghton Mifflin Company. All rights reserved.
23–38
Use with text pages 508–510.
Name
Chapter 23, Lesson 5
Reteach
Date
Problem Solving: Percent Problems
CA Standards
NS 1.2, MR 2.6
Example 1
Example 2
Find a number when a percent is known.
Find the percent of a number.
One day, the whale watching crew saw 80
humpback whales. That was 40% of all the
whales the crew saw during the entire week.
How many whales did they see in all?
Shelly saw 50 whales on a whale watching
trip. Thirty percent of the whales were
humpback whales. How many humpback
whales did Shelly see?
40% of what number equals 80?
What number is 30% of 50?
0.40 × n = 80
n = 0.30 × 50
0.40 × n
80
_______
= ____
0.40
0.40
80
n = ____
0.40
200
######################
0.40 # # #80.00
80
__
0
₎
n = 15
n = 200
Solution: The whale watching crew saw 200
whales in all.
0.30
×
50
______
0
+_____
1500
____
15.00
Solution: Shelly saw 15 humpback whales.
Use percents to solve each problem.
1.
Mr. Carson has 20 pencils. Of these,
55% are mechanical pencils. How many
mechanical pencils does Mr. Carson
have?
2.
Randy saw 35 hawks during hawk
migration last year. Seven of these were
red-tailed hawks. What percent were
red-tailed hawks?
Writing Math Suppose you are asked to find 80% of a number.
Will your answer be more or less than the original number? Explain how
you know.
Reteach
Copyright © Houghton Mifflin Company. All rights reserved.
23–44
Use with text pages 512–513.