Author note — to cover

Cover applying one percentage change n times as the multiplier raised to the power n, why adding percentages fails (two 10% rises give 21%, not 20%), and small-n money and population questions. Different consecutive changes are successive-changes; the compound interest formula, depreciation and how-long questions live in Growth and decay. Both tiers. (R9, R16)

• Fluency — direct questions on repeated percentage change, limited to this lesson's stated scope (4 questions).
• Application — use the same skill in unfamiliar or contextual questions without introducing a later method (4 questions).
• Check — questions built around the exclusions and likely misconceptions named in the lesson brief (4 questions).