Keystones — Lintel
Five GCSE retrieval questions · 25 December 2025 · mathsvault.uk/keystones
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1. Number Converting to standard form
50000000
Answer: 5 × 107 -
2. Algebra Factorising monic quadratics
Factorise: x² - 10x + 25
Answer: (x - 5)(x - 5) -
3. Geometry SOHCAHTOA — missing length
Adjacent = 18cm, angle = 38°. Find opposite
Answer: 14.cm -
4. Ratio Mixed ratio problems
Express the first part of 6:5 as a fraction in simplest form
Answer: 6⁄11 -
5. Statistics Mean
The mean of 6 numbers is 39. If 5 of them are 43, 20, 47, 37, 18, what is the missing number?
Answer: 69