Keystones — Lintel
Five GCSE retrieval questions · 13 March 2026 · mathsvault.uk/keystones
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1. Number Product of primes
Express 100 as a product of prime factors
Answer: 2² × 5² -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 24 and 3x - y = 25
Answer: x = 9, y = 2 -
3. Geometry Pythagoras — short side
Calculate the missing side: a = 12cm, c = 28cm
Answer: 25.3cm -
4. Ratio Combining two ratios
a:b is 3:4 and b:c is 1:2. Find a:b:c.
Answer: 9:12:24 -
5. Statistics Expected frequency
A bag has 4 red out of 15 balls. If you pick 54 times (with replacement), how many times would you expect red?
Answer: 14.4