Keystones — Lintel
Five GCSE retrieval questions · 21 January 2026 · mathsvault.uk/keystones
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1. Number Product of primes
Express 144 as a product of prime factors
Answer: 2⁴ × 3² -
2. Algebra Linear simultaneous equations
Solve: 5x + 3y = 37 and x + 3y = 17
Answer: x = 5, y = 4 -
3. Geometry Pythagoras — short side
Find b if a = 13cm and c = 21cm
Answer: 16.49cm -
4. Ratio Combining two ratios
a:b is 4:5 and b:c is 5:4. Find a:b:c.
Answer: 4:5:4 -
5. Statistics Expected frequency
A bag has 3 red out of 10 balls. If you pick 116 times (with replacement), how many times would you expect red?
Answer: 34.8