Is One a Prime Number? NO!

One is Not Prime

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

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

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

This poster can then be added to your Math Vocabulary Display as a form of Math Help reference material :)

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