Finding a percentage of a quantity
Convert percentages to multipliers and find parts of amounts quickly.
Key formulas
What this lesson covers
This lesson builds Secondary 2–3 skill in percentage of quantity. Read the key formulas, study the worked example, then attempt the written practice and the four-question MCQ review.
Method
Write every step. Name the rule you use (percentage of quantity) before substituting numbers. Keep units and signs visible until the final sentence.
Common mistakes
Students often rush the sign, use the wrong percentage base, or cancel terms instead of factors. Pause after each line and ask whether the step is reversible.
Exam habit
Underline the question verb (simplify, solve, factorise, find). Box the final answer and, where sensible, substitute back for a quick check.
Worked example
Worked example — percentage of quantity
Problem. Apply the method for percentage of quantity with the numbers 8 and 5.
Solution. Identify the rule for percentage of quantity. Substitute 8 and 5 carefully with signs in brackets if needed. Complete each operation on a new line. State the final answer clearly and check by reversing one step.
Review quiz
1 / 4Warm-up on percentage of quantity: what is 6+2?
Practice questions
- Practice 1 on percentage of quantity: compute with the value 20.
- Practice 2 on percentage of quantity: change the numbers and repeat the same method.
- Practice 3 on percentage of quantity: write one sentence explaining the key rule.
- Practice 4 on percentage of quantity: invent a similar exam-style question and solve it.
Study notes
What is the main idea of percentage of quantity?
Apply the stated formula or rule with clear steps, then check by reversing or substituting.
How should I revise this topic?
Cover the worked example, redo the practice without notes, then complete the MCQ set and log any wrong options.