The focus of this activity to challenge students to apply their knowledge of the four operations to solve a problem involving money. Students also need to demonstrate their ability to explain using evidence which option is the best.

##### Purpose
• Estimate solutions to problems
• Use the four operations and brackets to record a number sentence
• Apply knowledge of addition and subtraction to solve problems involving money
• Multiply decimals (money) by whole numbers
• Perform divisions of whole numbers where the result is a decimal
• Use calculations to compare options and explain which one is the best and why
• Show the strategy used to solve the problem
• Explain the strategy used to find a possible solution
• Check the solution to a problem using a model, visual method or calculations

##### WHOLE NUMBERS 1
• Recognise, represent and order numbers to at least tens of millions

• Use efficient mental and written strategies and apply appropriate digital technologies to solve problems (ACMNA291)

• Select and apply efficient mental and written strategies and appropriate digital technologies to solve problems involving addition and subtraction with whole numbers (ACMNA123)

##### FRACTIONS & DECIMALS 2
• Solve word problems involving the addition and subtraction of decimals, with and without the use of digital technologies, including those involving money
• Multiply decimals by whole numbers and perform divisions by non-zero whole numbers where the results are terminating decimals, with and without the use of digital technologies (ACMNA129)
• Compare, order, add and subtract integers (ACMNA280)

##### At the end of this lesson students should be able to answer the following questions
• How can we represent this problem?
• Which option do you think is better? Why?
• What strategy can you use to find a solution?
• Is there a more effective strategy?
• How can you check that your strategy is correct?
• Is there another method that could be used to find a solution to this problem?
• Could digital technology help? A calculator or a spreadsheet
• Can you use what you have discovered to explain which solution is better and why?