Keystones — Capstone
Five GCSE retrieval questions · 14 January 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: 6x² + 9x - 15
Answer: (3x - 3)(2x + 5) -
3. Geometry SOHCAHTOA — missing length
Adjacent = 25cm, angle = 31°. Find opposite
Answer: 15cm -
4. Ratio Reverse percentages
A price of £382.52 includes a 31% increase. What was the price before the increase?
Answer: £292.00 -
5. Statistics Mean
The mean of 5 numbers is 26. If 4 of them are 20, 17, 44, 36, what is the missing number?
Answer: 13