Key Concepts
- Applying the multiplication facts
- Associative(grouping) property of multiplication
3.4. Practice multiplication facts & The associate property: multiply with 3 factors
What is a multiplication fact?
A multiplication fact is an answer to a multiplication calculation.
Some examples of multiplication facts.
- 4 × 3 = 12 (the multiplication fact is 12)
- 7 × 8 = 56 (the multiplication fact is 56)
What is the associative property of multiplication?
The associative property of multiplication states that the way in which the numbers are grouped in a multiplication problem does not affect or change the product of those numbers.
Associative Property of Multiplication
Example for the associative property of multiplication.
(6 × 5 ) × 7 = 6 × (5 × 7)
(30) × 7 = 6 × (35)
210 = 210
3.4.1 Applying the multiplication facts
Example1:
Mr Ling arranged fruit salad bowls for his friends. He placed 7 rows of bowls, and each row had 4 bowls. How many fruits does the salad bowl Ling arrange?
Solution:
Find 7 x 4.
One way:
Step1: Draw a picture to find 7 x 4.
7 x 4 means 7 groups of 4
Combine groups to find the product.
4 feet in each section.
Step2: Multiply 7 x 4 = 28.
Another way:
Use known facts to find 7 x 4.
Use 5 and 2 as a fact to help.
Add 20 + 8 = 28.
Example2:
Mischa bought 6 packs of balls. Each packet has 3 balls. How many balls did Mischa buy?
Solution:
6 x 3 means 6 groups of 3.
Combine groups to find the product.
3 feet in each section.
6 x 3 = 18.
Another way:
Use known facts to find 6 x 3.
Use 4 and 2 as a fact to help.
Add 12 + 6 = 18.
3.4.2 Associative(grouping) property of multiplication
Example1:
Ricardo has 6 pages of stickers in an album. Each page has 6 rows with 4 stickers in each row. How many stickers are there in Ricardo’s album?
Solution:
Multiply (6 x 6) x 4.
One way’s
Find 6 x 6 first.
Another way:
6 x (6 x 4)
Find 6 x 4 first.
Example2:
Sarah is joining 5 sections of grid. Each section has 3 rows with 4 squares in each row. How many squares are there in these 5 sections? Find 5 x 3 x 4.
Solution:
Multiply (5 x 3) x 4.
One way’s
Find 5 x 3 first.
15 rows 4 squares in each row.
There are 60 squares in all.
Another way:
5x (3 x 4)
Find 6 x 4 first.
EXERCISE
- 1. Use known facts and strategies to find the product.
a. 8 x 2 =
b. 2 x 6=
c. 8 x 7= - 2. To find 8 x 4, how does knowing 6 x 4 = 24 help you?
- 3. What is 7 x 3?
- 4. Use the associative property of multiplication to find the missing number.
a. 7 x (2 x 4) = (7×2) x
b. 4x (3 x 2) = (4 x 3) x - Use the associative property of multiplication to find the product.
a. 2 x 3 x 5 =
b. 5 x 6 x 3= - Mary says she can find the product for 2 x 4 x 7 by solving 4 x2 x7. Is Mary correct? Explain.
- Which known facts can you use to find 9 x 5?
- Farmer has a garden with three sections of vegetables. Each section of vegetables has 5 rows with 6 plants in each row. How many plants does the farmer plant?
- A movie theatre has 2 sections. Each section has 6 rows and each row has 8 seats. Find the total number of seats are there in the movie theatre.
- Fill in the blanks for the following:
4x (3 x 2) = (4 x 3) x
6x (2 x 5) = (6 x2) x
(20 x 5) x 11 = 20 x (11x )
Related topics
Addition and Multiplication Using Counters & Bar-Diagrams
Introduction: We can find the solution to the word problem by solving it. Here, in this topic, we can use 3 methods to find the solution. 1. Add using counters 2. Use factors to get the product 3. Write equations to find the unknown. Addition Equation: 8+8+8 =? Multiplication equation: 3×8=? Example 1: Andrew has […]
Read More >>Dilation: Definitions, Characteristics, and Similarities
Understanding Dilation A dilation is a transformation that produces an image that is of the same shape and different sizes. Dilation that creates a larger image is called enlargement. Describing Dilation Dilation of Scale Factor 2 The following figure undergoes a dilation with a scale factor of 2 giving an image A’ (2, 4), B’ […]
Read More >>How to Write and Interpret Numerical Expressions?
Write numerical expressions What is the Meaning of Numerical Expression? A numerical expression is a combination of numbers and integers using basic operations such as addition, subtraction, multiplication, or division. The word PEMDAS stands for: P → Parentheses E → Exponents M → Multiplication D → Division A → Addition S → Subtraction Some examples […]
Read More >>System of Linear Inequalities and Equations
Introduction: Systems of Linear Inequalities: A system of linear inequalities is a set of two or more linear inequalities in the same variables. The following example illustrates this, y < x + 2…………..Inequality 1 y ≥ 2x − 1…………Inequality 2 Solution of a System of Linear Inequalities: A solution of a system of linear inequalities […]
Read More >>
Comments: