# 4.04 Multistep problems

Lesson

## Ideas

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.

### 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
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
Idea summary

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

### Outcomes

#### MA2-6NA

uses mental and informal written strategies for multiplication and division

#### MA2-8NA

generalises properties of odd and even numbers, generates number patterns, and completes simple number sentences by calculating missing values