Expressing one quantity as a percentage of another
Write A as a percentage of B using (A/B)×100%.
Key formulas
What this lesson covers
This lesson builds Secondary 2–3 skill in as a percentage of. 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 (as a percentage of) 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 — as a percentage of
Problem. Apply the method for as a percentage of with the numbers 9 and 6.
Solution. Identify the rule for as a percentage of. Substitute 9 and 6 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 as a percentage of: what is 7+3?
Practice questions
- Practice 1 on as a percentage of: compute with the value 21.
- Practice 2 on as a percentage of: change the numbers and repeat the same method.
- Practice 3 on as a percentage of: write one sentence explaining the key rule.
- Practice 4 on as a percentage of: invent a similar exam-style question and solve it.
Study notes
What is the main idea of as a percentage of?
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.