Is 1 a prime number?

<p>Title says it all.</p>

<p><a href="http://greatmathsgames.com/maths/prime-numbers/mathhelp1.gif%5B/url%5D"&gt;http://greatmathsgames.com/maths/prime-numbers/mathhelp1.gif&lt;/a&gt;&lt;/p>

<p>Did you really have to ask? (1 is not prime)</p>

<p>1 is not prime, but not composite either.</p>

<p>A prime number can only be evenly divided by 1 and itself. 1 is itself, and has to have another factor in order to be prime, which it doesn't have.</p>

<p>A composite number can be evenly divided by 1, itself, and one or more other numbers. 1 does not satisfy this, and cannot be composite.</p>

<p>Think about it this way: If it has 2 factors, it's prime. (2, 5, 7, etc.) If it has 3 or more factors, it's composite(4, 12, 24, etc.) If it has only one, then it is neither. Hope this helps!</p>

<p>Lmao at pic</p>

<p>No, but it is the loneliest number.</p>

<p>^The OP is unlikely to understand. :)</p>

<p>Nope. It's only got one factor.</p>

<p>There is no need to "infer" that 1 is not prime. The definition of prime numbers excludes it explicitly:</p>

<p>A prime number is a positive integer p>1 that has no positive integer divisors other than 1 and p itself.</p>

<p>^^^ I could not resist.</p>

<p>
[quote]
A prime number is a positive integer p>1 that has no positive integer divisors other than 1 and p itself.

[/quote]
</p>

<p>That is correct. But, considering the context of this forum, we should accept the "shortcut" version proposed by students as correct (needed two factors) although it is not the mathematical "reason." Fwiw, 1 used to be recognized as a prime number.</p>