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Which of the following is NOT a prime number?1). 612). 713). 694). 67 |
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Answer» Prime number: A natural number LARGER than unity is a prime number if it does not have other divisors except for itself and unity. As PROPERTIES of prime number (p): p > 3, p2 - 1 is COMPLETELY DIVISIBLE by 24. From options: 1) 61 ⇒ (612 - 1)/24 = (3721 - 1)/24 = 155 2) 71 ⇒ (712 - 1)/24 = (5041 - 1)/24 = 210 3) 69 ⇒ (692 - 1)/24 = (4761 - 1)/24 = 198.33 4) 67 ⇒ (672 - 1)/24 = (4489 - 1)/24 = 187 ∴ From above calculation 69 is not a prime number as it does not satisfy prime number properties. |
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