Five-Minute Check (over Lesson 2–6)

Main Idea

Key Concept: Addition Properties

Example 1:Name Addition Properties

Example 2:Use Properties to Add Whole Numbers

Example 3:Use Properties to Add Decimals

Example 4:Partial Sums of 10

• I will use Associative and Commutative Properties to add whole numbers and decimals mentally.

Name Addition Properties

Identify the addition property used to rewrite the problem below.

14 + (26 + 5) = (14 + 26) + 5

The grouping of the numbers to be added changes.

Answer: This is the Associative Property of Addition.

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

A. Commutative Property

B. Associative Property

C. Identity Property

D. Distributive Property

Identify the addition property used to rewrite the problem below.

3 + 5 + 9 = 5 + 3 + 9.

Use Properties to Add Whole Numbers

Aisling counted 21 gray cars, 13 white cars, and 19 red cars. How many cars did she count in all?

Since you can easily add 21 and 19, change the order and group those numbers together.

21 + 13 + 19 = 21 + 19 + 13 Commutative Property

= (21 + 19) + 13 Associative Property

= 40 + 13 Add 21 and 19 mentally.

= 53 Add 40 and 13 mentally.

Answer: So, Aisling counted 53 cars in all.

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

A. 15 movies

B. 20 movies

C. 35 movies

D. 40 movies

Louanne saw 12 scary movies, 15 action movies, and 8 comedy movies last year. How many did she see in all?

Use Properties to Add Decimals

Use properties of addition to find 1.7 + 0.6 + 0.3 mentally.

Since 1.7 + 0.3 = 2, group 1.7 and 0.3 together.

1.7 + 0.6 + 0.3 = 1.7 + 0.3 + 0.6 Commutative Property

= (1.7 + 0.3) + 0.6 Associative Property

= 2.0 + 0.6 Add 1.7 and 0.3 mentally.

= 2.6 Add 2.0 and 0.6 mentally.

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

A. 6.2

B. 6.0

C. 5.8

D. 5.1

Use properties of addition to find 5.1 + 0.2 + 0.9.

Partial Sums of 10Partial Sums of 10

Use properties of addition to find 24 + 17 mentally.

24 + 17 = (20 + 4) + (10 + 7) 24 = 20 + 4 and 17 = 10 + 7

= 20 + 10 + 4 + 7 Commutative Property

= (20 + 10) + (4 + 7) Associative Property

= 30 + 11 Add inside the parentheses.

= 41 Add 30 and 11 mentally.

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

A. 26

B. 50

C. 60

D. 61

Use properties of addition to find 35 + 26.

End of the Lesson

Five-Minute Check (over Lesson 2–6)

Image Bank

Math Tool Chest

Add and Subtract Decimals

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

(over Lesson 2–6)

A. 59.57

B. 60

C. 58.57

D. 58.6

Find 51.37 + 8.2.

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

(over Lesson 2–6)

A. 12.74

B. 12.73

C. 13.73

D. 12.75

Find 18.35 – 5.62.

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

(over Lesson 2–6)

A. 3.92

B. 2.019

C. 2.919

D. 2.28

Find 5.05 – 2.131.

1. A

2. B

3. C

4. D

A B C D

0% 0%0%0%

(over Lesson 2–6)

A. 7.201

B. 7.31

C. 7.206

D. 7.1

Find 3.19 + 4.016.