Keystones — Lintel
Five GCSE retrieval questions · 25 September 2026 · mathsvault.uk/keystones
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1. Number Product of primes
Express 180 as a product of prime factors
Answer: 2² × 3² × 5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 30 and 3x - y = 1
Answer: x = 3, y = 8 -
3. Geometry Pythagoras — short side
Calculate the missing side: a = 20cm, c = 27cm
Answer: 18.cm -
4. Ratio Combining two ratios
a:b is 1:2 and b:c is 3:4. Find a:b:c.
Answer: 6:12:16 -
5. Statistics Expected frequency
A bag has 4 red out of 13 balls. If you pick 98 times (with replacement), how many times would you expect red?
Answer: 30.2