Percentages — O/L Mathematics

What must I remember about Percentages?

• A percentage represents a fraction with a denominator of 100: x% = x / 100.
• Profit and Loss calculations: Profit % = (Profit / Cost Price) × 100%; Loss % = (Loss / Cost Price) × 100% (always calculated on Cost Price).
• Discounts and marked prices: Discount % = (Discount / Marked Price) × 100%; Selling Price = Marked Price - Discount.
• Simple Interest formula: I = (P × T × R) / 100, where P = Principal, T = Time in years, R = Annual interest rate; Total Amount A = P + I.
• Municipal assessment rates: Annual rates = (Assessed Annual Value × Rate %) / 100; quarterly rate instalment = Annual rates / 4.

Test yourself (1 minute)

1. Cost Price vs Selling Price baseline trap

   Profit and loss percentages MUST be calculated against Cost Price, NEVER against Selling Price (unless explicitly requested).

2. Quarterly rates division

   Remember that municipal rates are paid in 4 equal quarterly instalments; divide the annual rate by 4 to find the quarterly payment.

3. Time in years for simple interest

   If time is given in months, divide by 12 (e.g., 9 months = 9/12 = 3/4 years).

Practise Percentages questions today

Source: NIE G.C.E. (O/L) Mathematics Syllabus (Grade 10, Unit 13)

What should I study first?

What comes next?

Next in the syllabus

Where does Percentages fit in the syllabus?

Grade 10 · Term 2 · Grade 11 · Term 1