In 1741 Christian Goldbach conjectured that every even number could be written as a sum of two primes. [At the time 1 was considered a prime and so 2 = 1 + 1.] The conjecture has not been proven so there may be even numbers which cannot be so written. Also every number which is greater than 5 and is one fewer than a multiple of 6 cannot be so written.
21 and 32
65 and 77
Prime numbers have two factors, composite numbers have more than two.
Prime numbers have two factors; composite numbers have more than two.
The sum of two composite numbers is always a composite number or an even prime number. Composite numbers are integers greater than one that have at least one divisor other than one and themselves, meaning they can be formed by adding two composite numbers, which typically results in another composite. For example, adding 4 (a composite) and 6 (another composite) gives 10, which is also composite. However, the only exception occurs when the sum is 2, which is prime, though that situation is impossible with two composites since the smallest composite number is 4.
The sum of two prime numbers will be composite unless one of the prime numbers is 2.
The sum of any two prime numbers is not always a composite number. The sum of 2 and 11 is 13, and 13 is a prime number, not a composite number.
composite
The sum of any two prime numbers may or may not be prime. The sum of the two prime numbers 2 and 3 is the prime number 5, and the sum of the two prime numbers 5 and 7 is the composite number 12.
No, they are not. You can add two composite numbers, 15 and 14 for example, and get a sum, 29, that is prime.
Not always as for example 20+9 = 29 which is a prime number
Well, honey, let me break it down for you. The sum of two prime numbers can definitely be composite. Take 2 and 3 for example - both prime, but when you add them together, you get 5, which is still prime. But toss in 2 and 4, both prime, and you get 6, which is as composite as it gets. So, yes, the sum of two prime numbers can absolutely be composite.
21 and 32
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65 and 77
4nd 9.
The product of two prime numbers will be composite.