Keystones — Capstone
Five GCSE retrieval questions · 16 January 2026 · mathsvault.uk/keystones
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1. Number Rationalising the denominator
Rationalise the denominator: 6/√12
Answer: √3 (or 3√3⁄3) -
2. Algebra Factorising non-monic quadratics
Factorise: 16x² -4x - 6
Answer: (4x - 3)(4x + 2) -
3. Geometry SOHCAHTOA — missing length
Adjacent = 22cm, angle = 40°. Find opposite
Answer: 18.5cm -
4. Ratio Reverse percentages
A price of £603.88 includes a 24% increase. What was the price before the increase?
Answer: £487.00 -
5. Statistics Mean
The mean of 5 numbers is 22. If 4 of them are 43, 18, 36, 37, what is the missing number?
Answer: -24