Question:
Which one of the following is not a prime number?
Which one of the following is not a prime number?
Updated On: Oct 14, 2024
- 911
- 997
- 920
- 977
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The Correct Option is C
Solution and Explanation
911:Check divisibility by prime numbers up to √911 ≈ 30 (primes: 2, 3, 5, 7, 11, etc.).911 is not divisible by any of these primes.911 is a prime number.
997:Check divisibility by prime numbers up to √997 ≈ 31.997 is not divisible by any of these primes.997 is a prime number.
920: 920 is even, so it’s divisible by 2 (920 ÷ 2 = 460).920 is not a prime number.
977:Check divisibility by prime numbers up to √977 ≈ 31.977 is not divisible by any of these primes.977 is a prime number.
Conclusion:920 is not a prime number. The others (911, 997, 977) are prime.
997:Check divisibility by prime numbers up to √997 ≈ 31.997 is not divisible by any of these primes.997 is a prime number.
920: 920 is even, so it’s divisible by 2 (920 ÷ 2 = 460).920 is not a prime number.
977:Check divisibility by prime numbers up to √977 ≈ 31.977 is not divisible by any of these primes.977 is a prime number.
Conclusion:920 is not a prime number. The others (911, 997, 977) are prime.
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