2020 · Q1
The number 2 × 3 × 5 × 7 × 11 + 1 is
Elementary MathematicsNumber System
- Aa prime number
- Bnot a prime, but power of a prime
- Cnot a power of a prime, but a composite even number
- Dnot a power of a prime, but a composite odd number
Explanation
2×3×5×7×11 = 2310, so the given number is 2311. Test divisibility by every prime up to √2311 ≈ 48: 2311 leaves remainder 1 on division by 3, 7 (7×330 = 2310), 11 (11×210 = 2310), 13, 17, 19, 23, 29, 31, 37, 41, 43 and 47. Since it has no divisor ≤ √2311, it is prime. Hence the number is a prime number.