Keystones — Lintel
Five GCSE retrieval questions · 31 August 2025 · mathsvault.uk/keystones
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1. Number Converting to standard form
0.00021
Answer: 2.1 × 10-4 -
2. Algebra Factorising monic quadratics
Factorise: x² + 2x - 15
Answer: (x + 5)(x - 3) -
3. Geometry SOHCAHTOA — missing length
Hypotenuse = 40cm, angle = 52°. Find adjacent side
Answer: 24.6cm -
4. Ratio Mixed ratio problems
Simplify: 15:15:6
Answer: 5:5:2 -
5. Statistics Mean
The mean of 5 numbers is 40. If 4 of them are 47, 43, 31, 19, what is the missing number?
Answer: 60