Keystones — Capstone
Five GCSE retrieval questions · 19 September 2026 · mathsvault.uk/keystones
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1. Number Rationalising the denominator
Rationalise: 6/√5
Answer: 6√5⁄5 -
2. Algebra Factorising non-monic quadratics
Factorise: 8x² + 10x - 12
Answer: (4x - 3)(2x + 4) -
3. Geometry SOHCAHTOA — missing length
Adjacent = 15cm, angle = 60°. Find opposite
Answer: 26cm -
4. Ratio Reverse percentages
A price of £830.80 includes a 24% increase. What was the price before the increase?
Answer: £670.00 -
5. Statistics Mean
The mean of 5 numbers is 25. If 4 of them are 31, 34, 22, 20, what is the missing number?
Answer: 18