What the problems cover
The topics follow section 2 of Module 1 in the CSEC Mathematics syllabus (amended 2026, first exams May-June 2027): discount, sales tax, profit and loss and their percentages; marked, selling and cost price; hire purchase and mortgages; simple and compound interest; depreciation; currency conversion; rates and taxes, utility bills, invoices and shopping bills, salaries and wages, and insurance. Level 1 is one step, level 2 several steps, and the exam-style level asks for a table or bill to complete, like Paper 02 Question 1. Every name, price and rate is invented and printed in the question. The other-courses setting keeps to what Cambridge IGCSE 0580 and AQA GCSE 8300 ask, with VAT in place of sales tax.
ICSE Class 10 Commercial Mathematics (GST, recurring deposits, and shares and dividends, in rupees) has its own page.
An example from set SAVE29
In a sale, every price is reduced by 25%. Kezia paid $243.45 for a pressure cooker. The price paid is 75% of the original price, so the original price is $243.45 ÷ 75 × 100 = $324.60, and Kezia saved $324.60 − $243.45 = $81.15. Adding 25% of $243.45 instead gives $304.31, which is wrong: the 25% was taken off the original price, not the price paid. Open set SAVE29
Where marks are lost
The CSEC Mathematics subject reports name the slips below, and each one gets its own hint here when you check it. In May-June 2022, Question 1 (discount and sales tax among its parts) had a mean of 2.41 out of 9, and 72.07 per cent of candidates earned at most three marks.
- 2026: subtracting 0.15 from $16.40 for a 15 per cent reduction, and taking 15 per cent of the price paid off it to find the original price.
- 2025: not subtracting the principal from the compound amount, and using simple interest for compound interest.
- 2022: working out 15 per cent of a price that already includes the tax and taking it off, to find the price before tax.
- 2017: multiplying both the deposit and the instalment by 12, and not adding the units used to the last meter reading.
- 2016: working out 5 per cent of the marked price without taking it away, and not giving the profit as a percentage of the cost price.
Questions
How do you find the original price after a discount?
After a 15% reduction the price paid is 85% of the original price, so divide the price paid by 85 and multiply by 100. Taking 15% of the price paid and adding it on gives the wrong answer, because the 15% was worked on the original price, not on the price paid.
How do you work out the hire purchase price?
Add the deposit to the total of the instalments: deposit + number of instalments × each instalment. The deposit is paid once. The extra paid is the hire purchase price minus the cash price.
What is the difference between simple and compound interest?
Simple interest is worked on the principal every year: I = PRT ÷ 100. Compound interest is worked on the amount at the start of each year, so it grows: A = P(1 + r/100)ⁿ. The compound interest is A minus the principal.
What is the difference between straight line and reducing balance depreciation?
Straight line takes the same amount off every year: the rate times the cost. Reducing balance takes the rate off the value at the start of each year, so the yearly loss gets smaller: value = P(1 − r/100)ⁿ.
How do you calculate an electricity bill from meter readings?
The units used are the new reading minus the old reading. Multiply the units by the rate, using each rate only for its own band of units, then add any fixed charge, fuel charge and tax. To find a new reading, add the units used to the old reading.
Sources, checked 28 October 2026: CSEC Mathematics syllabus, amended 2026, with specimen papers and mark schemes (PDF); CSEC Mathematics subject reports (PDF): May-June 2016, May-June 2017, May-June 2022, May-June 2025, May-June 2026; Cambridge IGCSE Mathematics 0580 syllabus 2025 to 2027 (PDF); AQA GCSE Mathematics 8300 specification (PDF).