How many pairs of twin primes are there between 1 and 30?
- A.3
- B.4 ✓
- C.5
- D.6
Explanation: The primes up to 30 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29. Twin pairs: (3,5), (5,7), (11,13), (17,19) — 4 pairs.
Class 6 IMO Mathematics Olympiad practice · Number Sense · Factors, Multiples & Primes
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