Topics
5. Addition and subtraction
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Australia
Year 3

5.03 Notes and coins

Lesson
Practice
Lesson

Are you ready?

The strategy of  counting on  will be helpful in this lesson. Let's try a practice problem to review.

Examples

Example 1

Write the next number in the pattern:

1,\,3,\,5,\,7,\,9,\, 11,\,⬚

Worked Solution
Create a strategy

Get the next value by counting on to complete the pattern.

Apply the idea

Count on from 1 to 3 to get the increase of 2 as shown in the number line.

A number line with a point at 1 and an arrow pointing from 1 to 3.

So to get the next number in the pattern, we need to count on from 11 by 2. We can add them together using a place value table.

TensUnits
11
+02
13

The next number in the pattern is 13:1,\,3,\,5,\,7,\,9,\, 11,\,13

Idea summary

Counting on is helpful to find the next number in a pattern.

Coins

Countries around the world have different types of money (which are also called currencies), usually in the form of notes and coins. In Australia, we use dollars and cents as our currency.

Let's watch a video about the different Australian notes and coins and how we can use them in everyday life.

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Examples

Example 2

What is the value of each coin?

a
A 10 cent coin
Worked Solution
Create a strategy

The value of the coin is on the coin. If the coin is silver it is in cents. If the coin is gold it is in dollars.

Apply the idea

Since the coin is silver and there is a 10 on it, the value is 10 cents.

b
A 2 dollar coin
Worked Solution
Create a strategy

The value of the coin is on the coin. If the coin is silver it is in cents. If the coin is gold it is in dollars.

Apply the idea

Since the coin is gold and there is a 2 on it, the value is 2 dollars.

Idea summary

The value of a coin is written on the coin.

Silver coins are for cents, and gold coins are for dollars.

Add money

We can add notes and coins together to make a new total. Watch this video to see how.

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Examples

Example 3

Which of the following shows a total of \$22.50?

A
An image showing a 20 dollar note, a 2 dollar coin and a 50 cent coin.
B
An image showing a 20 dollar note, a 2 dollar coin and a 50 cent coin.
Worked Solution
Create a strategy

Add the value of each note and coin. Use this table of values to help you.

A table showing the value of 2 dollar, 1 dollar, 50 cent, 20 cent, 10 cent and 5 scent coins.
Apply the idea

All notes and gold coins are for dollars, and the silver coins are for cents. To add the values we can write \$5 as 5.00 and 50 cents as 0.50.

For Option A, write the addition of values in a vertical algorithm and add the digits in each column.

\begin{array}{c} & &2&0&.&0&0 \\ & &&2&.&0&0 \\ &+&&0&.&5&0 \\ \hline & &2&2 &. &5&0 \\ \hline \end{array}

The total amount of notes and coins in Option A is \$22.50.

For Option B, write the addition of values in a vertical algorithm. and add the digits in each column.

\begin{array}{c} & &2&0&.&0&0 \\ & &&5&.&0&0 \\ &&&1&.&0&0 \\ &+&&1&.&0&0 \\ \hline & &2&7 &. &0&0 \\ \hline \end{array}

The total amount of notes and coins in Option B is \$27.00.

So the answer is Option A, which equals \$22.50.

Idea summary

100 cents makes 1 dollar.

All notes have dollar values. The value is written on the note.

To add money we can write the values as decimals and add them using a vertical algorithm.

Outcomes

AC9M3A02

extend and apply knowledge of addition and subtraction facts to 20 to develop efficient mental strategies for computation with larger numbers without a calculator

AC9M3M06

recognise the relationships between dollars and cents and represent money values in different ways

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