Money, Finance and Consumer Numeracy
What you need to understand
This domain applies arithmetic to money and everyday consumer decisions. You should be able to calculate wages, overtime, deductions, GST, discounts, percentage profit and loss, simple interest and budgets. You need to read invoices, receipts, quotes and bank statements, compare prices per unit, and understand the difference between needs and wants when budgeting. Simple interest uses the formula I = P × r × t, where r is the annual rate as a decimal and t is in years. You should also understand the idea of compound interest at a basic level and know that interest on savings increases a balance while interest on a loan increases what you owe.
Traps to watch for
- GST. To add 10% GST, multiply by 1.1; to remove it from a GST-inclusive price, divide by 1.1 - not multiply by 0.9.
- Time in the interest formula. Months must be converted to years, so 6 months is 0.5 years.
- Unit price. Compare price per 100 g or per litre, not just the total price.
- Percentage profit. Profit percentage is usually calculated on the cost price, not the selling price.
Worked example
A loan of $4,000 attracts simple interest at 6% per year for 9 months. Interest = 4000 × 0.06 × 0.75 = $180. The trap is to use 9 instead of 0.75 for the time.
Rule of thumb
Write down the formula, convert time to years, then substitute and check the answer is sensible.
Mathematical Reasoning and Problem Solving in Context
What you need to understand
This domain tests whether you can read a real-world problem, decide what mathematics is needed, carry out the steps and communicate a sensible answer. You should be able to identify the information that matters and ignore what does not, choose an appropriate operation, work through multi-step problems, and check that the answer fits the context. You should be able to explain your reasoning in words, justify a choice between options, and recognise when a problem has no single correct answer but a best-supported one. Estimation, trial and improvement, and working backwards are all valid strategies.
Traps to watch for
- Answering the wrong question. Underline what is actually being asked before calculating.
- Missing a step. Many problems need two or three operations in sequence.
- Unrealistic answers. A person's weekly wage of $500,000 or a negative length signals an error.
- Assuming all options are comparable. Compare like with like, using the same units and time period.
- Over-precision. Do not give an answer to five decimal places when the context calls for whole dollars.
Worked example
A family has a monthly income of $5,200. Rent is $1,600, groceries $900, utilities $350 and transport $400. They want to save 10% of income each month. How much is left for other spending?
Total committed = 1600 + 900 + 350 + 400 = $3,250. Savings target = 10% of $5,200 = $520. Remaining = 5200 − 3250 − 520 = $1,430. The trap is to forget the savings target as an expense.
Rule of thumb
Read twice, list the given information, plan the steps, calculate, then check against the context.