When we count the value of coins, work out the cost of groceries or work out the change the shopkeeper will give us, we are using maths. Let's look at how we do this now.

Counting coins

In Dollars and cents, we looked at how we can we count money. Just like when you count up by twos, fives or tens with numbers, we can count the value of coins the same way. You can practise now using this widget.

In Purchases and change, we looked at how to work out the total cost of a purchase. Here is a summary.

To work out the total cost

To work out the total cost, we add the price of each item. For example, if I bought an apple for $50$50 cents and a bottle of water from $\$1.20$$1.20, this is how I would work out the total cost:

$0.50+1.20=\$1.70$0.50+1.20=$1.70

This means the total amount I would have to pay the shopkeeper is $\$1.70$$1.70.

Example

Question 2

Valentina earns $\$26$$26 the first weekend she babysits, and $\$49$$49 the second weekend she babysits. Over the two weekends, how much does she earn in total?

To work out the change

Remember change is the difference between the total cost of a purchase and the amount that was paid. To find the difference, we use subtraction. Using the example above, if I owed $\$1.70$$1.70 and paid with a $\$2$$2 coin, the shopkeeper would calculate the change like this:

$2.00-1.70=\$0.30$2.00−1.70=$0.30

This means the shopkeeper would give me $30$30 c change.

Examples

Question 3

How much change would you receive from $\$10$$10 if you spent:

$\$4.50$$4.50?

$\$3.95$$3.95?

Terms used in Money Questions

There is a specific language used in money maths. Here are a couple of common ones. Remember you can click on the word to see more of an explanation.

Budget- an allocated amount of money.

Discount/ percentage discount- an amount of money (usually a percentage amount) that is subtracted from the total cost of an purchase.

Examples

Question 4

Jack budgeted $\$31$$31 for his father's birthday present.

However, it actually cost him $\$34.74$$34.74.

By how much was Jack over budget?

Question 5

Jimmy decides to give $10%$10% of his pocket money to charity each week.

If he earns $\$14$$14 pocket money per week, how much does he give to charity?

How much money does he have left?

Outcomes

GM4-1

Use appropriate scales, devices, and metric units for length, area, volume and capacity, weight (mass), temperature, angle, and time