Solving Exercise 3 on Pages 51 and 52 of Math 5 Textbook

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Ngày cập nhật gần nhất: 15/4/2026

Solving Exercise 3 on Pages 51 and 52 of Math 5 Textbook: Summing Multiple Decimal Numbers, Using Commutative and Associative Properties for Calculation

Guidance for Solving Exercise 3 on Pages 51 and 52 of Math 5 Textbook

Problem Statement:
Using commutative and associative properties to calculate:
a) 12.7 + 5.89 + 1.3 ;
b) 38.6 + 20.09 + 7.91 ;
c) 5.75 + 7.8 + 4.25 + 1.2 ;
d) 7.34 + 0.45 + 2.66 + 0.55

Solution Method:
Remember:
- Commutative property of addition: a + b = b + a (when swapping addends in a sum, the sum remains unchanged)
- Associative property of addition: (a + b) + c = a + (b + c) (when adding the sum of the first two numbers with the third number, we can also add the first number with the sum of the second and third numbers without changing their values.)

Answers:
a) 12.7 + 5.89 + 1.3
= (12.7 + 1.3) + 5.89
= 14 + 5.89
= 19.89

b) 38.6 + 20.09 + 7.91
= 38.6 + (2.09 + 7.91)
= 38.6 + 10
= 48.6

c) 5.75 + 7.8 + 4.25 + 1.2
= (5.75 + 4.25) + (7.8 + 1.2)
= 10 + 9
= 19

d) 7.34 + 0.45 + 2.66 + 0.55
= (7.34 + 2.66) + (0.45 + 0.55)
= 10 + 1
= 11.

Here is the solution guide for exercise 3 on pages 51 and 52 of Math 5 textbook. Additionally, this section includes 2 more exercises: Solving Exercise 1 on Pages 51 and 52 of Math 5 Textbook and Solving Exercise 2 on Pages 51 and 52 of Math 5 Textbook. Let's explore the solution guide for exercises on pages 51 and 52 of Math 5 to excel in Grade 5 Mathematics!

Frequently Asked Questions

What are the commutative and associative properties of addition?

The commutative property states that changing the order of addends does not change the sum, while the associative property indicates that the way numbers are grouped in addition does not affect the total. Both properties are essential for simplifying calculations.

How do you use properties to sum multiple decimal numbers?

To sum multiple decimal numbers, apply the commutative and associative properties to rearrange or group the numbers for easier calculations. This method helps streamline the process and ensures accuracy in results.

What is the solution for adding 12.7, 5.89, and 1.3?

The sum of 12.7, 5.89, and 1.3 is calculated as follows: first group 12.7 and 1.3, giving 14. Then add 5.89, resulting in a total of 19.89.

Can you explain how to solve the exercise with 38.6, 20.09, and 7.91?

To solve the exercise with 38.6, 20.09, and 7.91, group 20.09 and 7.91 to simplify to 10, then add that to 38.6. This results in a final answer of 48.6.

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