# In school, were you taught that 1 is a prime number?

**URL:** <https://boards.straightdope.com/t/in-school-were-you-taught-that-1-is-a-prime-number/653655>\
**Category:** In My Humble Opinion\
**Created:** [March 22, 2013, 5:45pm UTC](https://boards.straightdope.com/t/in-school-were-you-taught-that-1-is-a-prime-number/653655 "2013-03-22T17:45:20Z")\
**Posts on this page:** 2\
**Page:** 6

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**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\
**Post date:** [March 25, 2013, 5:45pm UTC](https://boards.straightdope.com/t/in-school-were-you-taught-that-1-is-a-prime-number/653655/101 "2013-03-25T17:45:00Z")

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> [@Trinopus](#):
>
> And yet, when calculating “perfect numbers,” you include one. Six is a perfect number, and so is 28…but only when you include 1 as one of the divisors.

Of course 1 is a divisor. What does that have to do with its being prime?

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**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\
**Post date:** [March 25, 2013, 6:48pm UTC](https://boards.straightdope.com/t/in-school-were-you-taught-that-1-is-a-prime-number/653655/102 "2013-03-25T18:48:09Z")

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An interesting reason why the “Is 1 prime?” issue isn’t ancient seems to be that …  
[One wasn’t even considered a number, at least by Europeans, prior to the texts of Simon Stevin!](http://books.google.co.th/books?id=uTytJGnTf1kC&pg=PA28&lpg=PA28) :dubious:

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