Which of the following is NOT a pair of twin primes?
- A.(17, 19)
- B.(29, 31)
- C.(41, 43)
- D.(23, 27) ✓
Explanation: 27 = 3×3×3 is not prime, so (23, 27) can't be a twin-prime pair. The other three pairs are both prime and differ by 2.
Class 6 IMO Mathematics Olympiad practice · Number Sense · Factors, Multiples & Primes
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