Keystones — Lintel
Five GCSE retrieval questions · 1 October 2025 · mathsvault.uk/keystones
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1. Number Converting to standard form
43000000
Answer: 4.3 × 107 -
2. Algebra Factorising monic quadratics
Factorise: x² + 2x - 3
Answer: (x + 3)(x - 1) -
3. Geometry SOHCAHTOA — missing length
Adjacent = 30cm, angle = 42°. Find opposite
Answer: 27cm -
4. Ratio Mixed ratio problems
Simplify the ratio 2m:200cm
Answer: 1:100 -
5. Statistics Mean
The mean of 6 numbers is 22. If 5 of them are 37, 42, 15, 20, 29, what is the missing number?
Answer: -11