*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.