Talk:0.999.../Arguments

This page is for arguments over the validity of 0.999.... This is not an archive; you may feel free to edit this page. Please use this page for comments not directly relevant to improving the article 0.999....

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Frequently asked questions

Q: You guys talk a lot about real analysis, limits, and calculus; shouldn't this just be about arithmetic?

A: Unfortunately, in order to formally prove many qualities of numbers, one often has to resort to higher mathematics: real analysis in the case of real numbers, number theory in the case of integers, and so forth. The article and arguments page both aim to be understandable to all, but, since many skeptics ask for formal proofs, higher mathematics will inevitably come into play.

Q: Person X made a pretty convincing argument that

0.999...\neq 1

! Those who say otherwise are giving arguments I can't understand.

A: Before believing an argument, check sources, responses, and record. The main article is well-sourced, whereas arguments against generally cite (if anything) non-mathematical sources such as online message boards and dictionaries. Also, although most people are trying to write something everyone can understand, some arguments, in relying on higher mathematics, will not be easy to follow for all. Still, try to follow those you can. Finally, those who firmly believe that mainstream mathematics is mistaken will generally reveal their lack of rigor and/or contempt for experts and others who disagree with them. Before replying, read their other contributions to make sure you aren't siding with someone you yourself would not trust.

Q: I have a mathematical question.

A: Please check the FAQ on the talk page.

Q: Do any reliable sources side with the students' stubborn feeling that 0.999... should be less than 1?

A: Yes. See the section on infinitesimals in the main article.

This page was nominated for deletion. Please review the prior discussions if you are considering re-nomination:

Keep, 2014-10-16, see discussion.
Keep, 2010-12-01, see discussion.
Keep, 2009-04-13, see discussion.
Keep, 2007-12-05, see discussion.

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