# Prime Numbers - Is One a Prime Number? - One is NOT a Prime Number!!!

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- Is One a Prime Number?

## Is One a Prime Number? No!!!

Summary: Many people hold the misconception that one is a prime number. This mathematics poster explains it all.

## One is Not Prime

I usually try to introduce the concept of 1 not being prime by examining the mathematical definition closely.

'For a number to be prime it must have TWO different factors'.

In 1's case its factors are 1 and 1.

For a number to be prime it must be able to be divided by itself AND 1.

In the case of 1 'itself ' IS one.

NB This Prime Number Math Wall Poster has had a rather significant update since I first made it c. 2004. Click on the image above to grab the new poster.

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