what is a prime number and why?

Answer 1

There is an excellent description of prime numbers at:
http://en.wikipedia.org/wiki/Prime_numbers

Answer 2

In mathematics, a prime number (or a prime) is a natural number that has exactly two (distinct) natural number divisors, which are 1 and the prime number itself. There exists an infinitude of prime numbers, as demonstrated by Euclid in about 300 B.C.. The first 30 prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, and 113 (sequence A000040 in OEIS); see the list of prime numbers for a longer list.

The property of being a prime is called primality, and the word prime is also used as an adjective. Since 2 is the only even prime number, the term odd prime refers to all prime numbers greater than 2.


(Ancient Greeks such as Pythagoras are believed to have been the first to study prime numbers, and the simple sieve method for finding them is attributed to Eratosthenes.

Until the 19th century most mathematicians considered the number 1 a prime, and there is still a large body of mathematical work that is still valid despite labelling 1 a prime, such as the work of Stern and Zeisel. Henri Lebesgue is said to be the last professional mathematician to call 1 prime. The change in label occurred so that it can be said 'each number has a unique factorization into primes.' [1] See also Arguments for and against the primality of 1.

For a long time, prime numbers were thought as having no possible application outside of number theory; this changed in the 1970s when the concepts of public-key cryptography were invented, in which prime numbers formed the basis of the first algorithms such as the RSA cryptosystem or the Diffie-Hellman key-exchange algorithm.)

Answer 3

a prime number is a number that can only be divided by itself as well the number one. for exampl 13 can only be divided by one and 13 to get a whole number as an answer. the same is true for 2, 5, 7, 11 etc. however it does not include all odd numbers, though a large number of prime numbers are odd numbers. for example, the number 9 can be divided by 1, 3 and 9. so it is not a prime number because it has more than 2 factors(numbers a number can be divided by). however, the number 1 is NOT a prime number, though most say it is. this is cause number 1 can only be divided by 1. it has only one factor, whereas prime numbers have 2, so thus, it is not a prime factor. hope tt helped :)

Answer 4

A prime number is a whole number that is only divisible by itself and 1. There are infinite amounts of prime numbers the most common... 1 , 2 , 3 , 5 , and 7... It's mostly odd numbers because even numbers are always divisible by 2 except 2 itself... So prime numbers are number that are only divisible by 1 and themselves.

Answer 5

Prime numbers are the numbers which have only two factors the number itself and '1'. Such number are called prime numbers. Eg: 5,7,13. etc. Prime numbers play an important role in the field of cryptography for developing encryption algorithms because of its unique property. As it is not divisible by ant other number hence to find a number prime is a tedious task.

Answer 6

A prime number is a number that can only be divided by one or itself with no decimal points after it. For example, 3 is a prime number because it can only be divided by 3 or 1. If you try to divide it by 2, you'll get 1.5 as the answer.

Answer 7

If u know the meaning of the word "prime",then u will know the meaning of prime number.If u dont know the meaning of prime,u can actually use politics to find the answer.I sure u know that every government consists of the president,prime minister,officials and people of the public.I sure u know that government can only have one prime minister.If u think is yes,then you will know the answer.Why?There is a word here in my answer that is the answer.

Answer 8

A Prime Number has only two factors. They are one and itself. For Ex: if u take 2, 1,2 are its factors. Apart from 1, it has only one factor. Hence it is called Prime Number. Prime means only one. 1 is not considered since it is Universal Factor.

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Answer 9

a prime number is a number that can be divided only by itself, ie 3, 5, 7, 11, 13 etc etc

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Answer 10

A prime number is a number whose only factors are itself and 1.

Answer 11

What = Prime numbers are numbers that only have 2 factors; itself and 1. They are numbers that can not be factored.