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Question

The product of two consecutive prime numbers is 437. The difference between these two prime numbers is:

This question was previously asked in
RRB Technician 2026 Grade 3 Question Paper (7-Oct-2026) (Shift 3)
The correct answer is

4

Since \(\sqrt{437} \approx 20.9\), one prime factor lies below 21 and the other above it.

Testing primes below 21: 437 ÷ 19 = 23, so 437 = 19 × 23.

19 and 23 are consecutive primes (no prime lies between them, as 20, 21 and 22 are composite). Difference = 23 – 19 = 4.

Check: 19 × 23 = 19 × 20 + 19 × 3 = 380 + 57 = 437.

Hence, 4.

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