Difference between revisions of "Prime number"

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=== Twin Primes ===
 
=== Twin Primes ===
Two primes that differ by exactly 2 are known as [[twin primes]].  The following are the smallest examples:
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Two primes that differ by exactly 2 are known as [[twin primes]].  The following are the smallest examples:<br>
3, 5
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3, 5<br>
5, 7
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5, 7<br>
11, 13
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11, 13<br>
17, 19
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17, 19<br>
29, 31
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29, 31<br>
41, 43
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41, 43<br>
  
  

Revision as of 00:35, 20 June 2006

A prime number (or simply prime) is a positive integer $p>1$ whose only positive divisors are 1 and itself. Note that $1$ is usually defined as being neither prime nor composite because it is its only factor among the natural numbers.


Famous Primes

Fermat Primes

Mersenne Primes

Twin Primes

Two primes that differ by exactly 2 are known as twin primes. The following are the smallest examples:
3, 5
5, 7
11, 13
17, 19
29, 31
41, 43


Advanced Definition

When the need arises to include negative divisors, a prime is defined as an integer p whose only divisors are 1, -1, p, and -p.