Keystones — Capstone
Five GCSE retrieval questions · 18 January 2026 · mathsvault.uk/keystones
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1. Number Rationalising the denominator
Rationalise: 2/√5
Answer: 2√5⁄5 -
2. Algebra Factorising non-monic quadratics
Factorise: 12x² + 14x - 10
Answer: (4x - 2)(3x + 5) -
3. Geometry SOHCAHTOA — missing length
Adjacent = 14cm, angle = 31°. Find opposite
Answer: 8.4cm -
4. Ratio Reverse percentages
A price of £871.92 includes a 26% increase. What was the price before the increase?
Answer: £692.00 -
5. Statistics Mean
The mean of 6 numbers is 24. If 5 of them are 42, 46, 30, 22, 17, what is the missing number?
Answer: -13