Solve problems involving profit and loss, with and without digital technologies (ACMNA189)

LO: To calculate percentage profit/loss of a quantity


  • How to calculate the percentage of a value.

  • Profit is money gained from a transaction

  • Loss is the money lost from a transaction.


  • That a quantity can be increased/decreased by a certain amount.

  • Profit is made when a gain in money from a transaction occurs.

  • Loss is made when a lost in money from a transaction occurs.


  • I can calculate the profit/loss of a quantity.

Teacher Notes

100% of an item means the full number or price.
Selling Price means how much the item was sold for.
Cost Price (original price) means how much the item was originally bought for.
Percentage profit means that I sold the item for more than it was originally worth. (Selling Price > Cost Price)
Percentage loss means that I sold the item for less than it is worth. (Selling Price < Cost Price)

To find percentage profit:
Selling Price – Cost Price (original price) = Profit
Profit / Cost Price (original price) = Percent Profit

One common misconception when calculating the percentage profit or loss is understanding that profit or loss is divided by the original cost. This is because we need to see the profit or loss compared to the original cost of the item and not what the selling price of the item is.

Profit = Making Money

Loss = Losing Money

To find percentage profit:
Selling Price – Cost Price = Profit
Profit / Cost Price = Percent Profit

Teaching Ideas

Introduce the share market to the class by spending 5 -10 minutes discussing the history of the share market. Advise students that they
will be using information in the actual share market for this activity.

Divide students into pairs or small groups and provide each group with a set amount (e.g. $5000) to ‘invest’.

Each group then uses the internet to research share prices online. Ask students to decide on a company to invest their money in and
determine how many shares they can purchase given the current share purchase price. You may like to guide students towards certain
companies or give them a list to select from, so they don’t take too much time researching. Alternatively, you may like to provide students with a list of factors to consider when investing (stability of the share price, longevity of the company etc) to help them make their decision.

Advise each group that they will need to track the value of their shares over the next fortnight and determine when they will sell their
shares to try and make the largest profit. Each group will need to keep a record of the daily share price and decide on which day they
think they would sell their shares and what their profit/loss would be.

Even if a group decides to ‘sell’ their shares on Day 1 they should keep recording the daily share price for a fortnight to see if they made
the ‘right decision’ for the best profit. You may then ask each group to present their profit (or loss) to the class and see which group made the largest profit.

Alternatively, you may offer groups the option to sell part of their shares and reinvest their money in another company before the fortnight is finished. The aim is for students to reinvest their money to
compete with other groups, for the highest profit.


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