Topics
4. Multiplication and division
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Australia
Year 4

4.04 Multistep problems

Lesson
Practice
Lesson

Are you ready?

We have learned to write a number problem from a  story problem with multiplication or division  already.

Examples

Example 1

There are 3 rows of trees in a field, with 10 trees in each row.

a

Write a number sentence for this story problem.

Worked Solution
Create a strategy

There are an equal number of trees in each row, so we can think of each row as a group.

Apply the idea

There were 3 groups of 10 trees, and "groups of" means multiply.

Number sentence =3\times 10

b

How many trees are there in the field?

Worked Solution
Create a strategy

We can find the number of trees in the field by solving the number sentence in part (a).

Apply the idea

3\times 10 = 30

There are 30 trees.

Idea summary

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

Multi-step problems

What happens if our story has more than one part to it? Let's see how to turn that into a number problem with multiplication and division.

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Examples

Example 2

There are 2 flower beds in Irene's backyard. Each flower bed has 4 strawberry plants.

a

How many strawberry plants are there in total?

Worked Solution
Create a strategy

There are 2 groups of 4 strawberry plants. "Groups of" means multiply.

Apply the idea
\displaystyle \text{Total strawberry plants}\displaystyle =\displaystyle 2\times 4Multiply 2 by 4
\displaystyle =\displaystyle 8
b

If each plant has 3 strawberries growing on it, how many strawberries are there in total?

Worked Solution
Create a strategy

Multiply the number of strawberry plants in part (a) by the number of strawberries on each plant.

Apply the idea
\displaystyle \text{Strawberries}\displaystyle =\displaystyle 8\times3Multiply 8 by 3
\displaystyle =\displaystyle 24
Idea summary

We can use pictures, numbers or symbols for our problems, so it helps to know how to use each method.

The image shows 3 times 4 in pictures, words and symbols. Ask your teacher for more information.

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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