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How do you know that all even numbers greater than 2 must be prime?
Wiki User
∙ 13y ago
they're not!
Wiki User
∙ 13y ago
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How do you know that 2 and 3 are the only conseqtive prime numbers?
All the other prime numbers are odd. Every other pair of odd numbers has at least one even number between them. Even numbers greater than two are not prime.
Are all even numbers composite why?
no all even numbers except 2
Is 294 and 256 a co prime number?
No. Even numbers can't be co-prime.
How do you prove that if the sum of two prime numbers is prime then one of the numbers is 2?
We know that a prime number is a positive integer greater than 1, whose divisors are 1 and itself. We know that the only even prime number is 2. That means that all other prime numbers are odd numbers.We know that when we add two odd numbers the result is an even number, which are not prime numbers (expect 2, and 2 = 1 + 1 where 1 is odd but is neither prime nor composite). Thus adding two odd prime numbers cannot give us another prime number. We show that the conclusion follows from the premise:Assume that r = p + q where all r, p and q are prime numbers, then we have that ris either even or not:* If r is even then r is at least 4 (the smallest number which is the sum of two primes) and thus not a prime number. This contradicts the assumption that r is a prime number, and therefore we conclude that r is not even. * If ris odd then either p or q must be odd and the other one must be even, since both p and q are prime numbers one of them must be 2 (the only even prime number). 2 + 3 = 5, 2 + 17 = 19, are examples of such numbers. See http://en.wikipedia.org/wiki/Twin_prime for more.
Why is it difficult to find even prime numbers?
even numbers are 2.4,6,8,10,12,14,16,18,20. if you skip count by two you will know what an even number is,and ther is more numbers than what i said
How do you know when two pairs of numbers will have an LCM that is less than the product of the numbers?
When their GCF is greater than 1. When they have prime factors in common.
What are two prime numbers?
i know what 2 prime numbers are. you want to know? do you really want to know. well, heres the answer. i don't know what 2 prime numbers are but i do know what 2 prime numbers are. sorry. hahaha. :)
Julia says that prime numbers have to be odd and composite numbers have to be even. is she correct explain how you know?
Julia is incorrect. 2 is an even prime number and 9 is an odd composite number.
Why are 2 and 3 consecutive prime numbers?
A prime number is a number only divisible by 1 and itself, since nothing else goes into 2 but 1 and 2 and nothing goes into 3 but 1 and 3 they are both prime and since 3 goes after 2 they are consecutiveAnd they are the ONLY consecutive prime numbers because if you have one prime number (i.e. 29), then there always is an even number right after the prime number (i.e. 30 comes right after 29), and consecutive means "right next to," right? And we all know that even numbers can always be divided in half, so 2 and 3 are the only consecutive prime numbers.1 is not a prime so that (1,2) is not a pair of consecutive integers that are prime. So, if there is another opair of consecutive numbers that are prime, they must be larger than (2,3) - ie the smaller of the pair must be greater than 2.Now any pair of consecutive numbers must have one odd and one even number. Therefore, the candidate pair must contain an even number which is greater than 2. But all even numbers greater than 2 are divisible by 2 and so are composite (non-prime). So every such candidate pair contains an odd number which may or may not be prime, and an even number which is definitely not a prime.
How do you know if a number greater than 100 is a prime number?
You try dividing it by all prime numbers less than of equal to its square root.
Is it true that the sum of two sequential prime number number is not prime?
We know that a prime number is a positive integer greater than 1, whose divisors are 1 and itself. We know that the only even prime number is 2. That means that all other prime numbers are odd numbers.We know that when we add two odd numbers the result is an even number, which are not prime numbers (expect 2, and 2 = 1 + 1 where 1 is odd but is neither prime nor composite). Thus adding two odd prime numbers cannot give us another prime number.We show that the conclusion follows from the premise:Assume that r = p + q where all r, p and q are prime numbers, then we have that r is either even or not:If r is even then r is at least 4 (the smallest number which is the sum of two primes) and thus not a prime number. This contradicts the assumption that r is a prime number, and therefore we conclude that r is not even.If r is odd then either p or q must be odd and the other one must be even, since both p and q are prime numbers one of them must be 2 (the only even prime number).2 + 3 = 5, 2 + 17 = 19, are examples of such numbers.
How do you know that a certain large number is a prime number espicially when it is a large number?
If it's even and greater than two, it's not prime. If you know the divisibility rules, you can eliminate 3 through 10 as factors. Through trial and error, you can eliminate 11, 13, 17 and 19 and so on until you get bored. That leaves numbers like 1849 which looks prime but is actually the product of 43 and 43. For large numbers like that, Google "list of prime numbers" and click on the first 10000 primes. That will let you know for certain.
