Topics
4. Multiplication and division
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Australia
Year 4

4.03 Story problems

Lesson
Practice
Lesson

Are you ready?

Sometimes, we need to know how to write a number sentence from a  story problem  .

Examples

Example 1

There were 2 rows of trees in a field, with 3 trees in each row.

Write a number sentence for this story problem to find the total number of trees in the field.

Worked Solution
Create a strategy

Since there is an equal number of trees in each row, we can think of each row as a group.

Apply the idea

There were 2 groups of 3 trees, and "groups of" means multiply.

Number sentence =2\times 3

Idea summary

If we need to find the total for multiple equal groups, we need to multiply.

Story problems with multiplication and division

How do we know if we need to multiply or divide, when we have a story problem? Let's see if we can find some clues, in this video.

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Examples

Example 2

A teacher wants to divide up her class of 6 students evenly onto 3 tables.

a

Write a number sentence for this story problem.

Worked Solution
Create a strategy

The word "divide" tells us that we should use division.

Apply the idea

The teacher will have to divide the 6 students into 3 equal groups.

Number sentence = 6\div3

b

How many students will there be at each table?

Worked Solution
Create a strategy

To find the number of students at each table we need to solve the number sentence from part (a).

Apply the idea

The picture shows 6 squares split into 3 rows:

An array of 6 squares with 3 rows and 2 columns.

There are 2 squares in each row. So: 6\div 3 = 2.

So there will be 2 students at each table.

Idea summary

  • If we have a total to share, we use division to work out how many groups, or how many in each group.

  • If we have a number of equally sized groups, we need to multiply to work out the total.

  • Multiplication and division are opposites but you can use fact families to help you to solve questions.

Outcomes

AC9M4N06

develop efficient strategies and use appropriate digital tools for solving problems involving addition and subtraction, and multiplication and division where there is no remainder

AC9M4N08

use mathematical modelling to solve practical problems involving additive and multiplicative situations including financial contexts; formulate the problems using number sentences and choose efficient calculation strategies, using digital tools where appropriate; interpret and communicate solutions in terms of the situation

AC9M4A02

recall and demonstrate proficiency with multiplication facts up to 10 x 10 and related division facts; extend and apply facts to develop efficient mental strategies for computation with larger numbers without a calculator

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