# 7777777 and .999... == 1

**URL:** <https://boards.straightdope.com/t/7777777-and-999-1/693964>\
**Category:** The BBQ Pit\
**Created:** [July 24, 2014, 7:51pm UTC](https://boards.straightdope.com/t/7777777-and-999-1/693964 "2014-07-24T19:51:33Z")\
**Posts on this page:** 1\
**Showing post:** 1

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**Author:** ![Stealth\_Potato](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Stealth\_Potato](https://boards.straightdope.com/u/Stealth_Potato)\
**Post date:** [July 24, 2014, 7:51pm UTC](https://boards.straightdope.com/t/7777777-and-999-1/693964/1 "2014-07-24T19:51:33Z")

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> [@](#):
>
> _Mad call I it; for, to define true madness,  
> What is’t but to be nothing else but mad?_
> 
> - Polonius

Regarding [this infernal, interminable thread](http://boards.straightdope.com/sdmb/showthread.php?t=32760).

Contrary, perhaps, to the title, this is not a pitting of Mr. **7777777** , as mere forces of nature are without reason, wholly idiotic and innocent, and therefore above reproach. You’d with as much consequence chastise a thunderstorm for drowning your azaleas. No, friends, this is a pitting of the rest of you. You know who you are.

Having maintained a studied but aloof interest in the progress of the aforementioned thread, I have occasionally had to resist an impulse to add my own voice to the well-meaning chorus of explanations, expositions, and pedagogical discursions that **7777777** ’s religious fervor seems to demand.

I understand the temptation, believe me. Man is always loath to let a raincloud have the last word. I myself once spent a pleasant afternoon explaining the proof of Burnside’s lemma to a ladybug, which elementary result of group theory it stubbornly defied. Regrettably, it flew away just as I was demonstrating the fallacy of one of its counter-rebuttals. I felt cheated, and naturally woeful that my efforts had not reduced the amount of ignorance in the world by even one iota.

I still occasionally slip into error, but I have learned my lesson sufficiently to be capable of recognizing the fault which several of our esteemed colleagues are, alas! indulging.

That 0.9̅ is another notation for 1 is a simple and obvious fact; a systemic failure to understand any of the dozens of accessible, correct, and concise proofs of this fact can only be explained by a full-stack, no-holds-barred, aggressive and wilful discomprehension of not just the mere concept of notation, but every tenet foundational to formalism of any kind. Such a mind should be consigned to a cell in Broadmoor, or made the chair of a Liberal Arts college, but should on no account be argued with.

I pray, with little hope, for an end to the madness.

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