Talk:Friendly number

I agree with the unsigned comment below that the description here is difficult to understand and weak.

West in--67.0.42.232 (talk) 21:11, 26 February 2021 (UTC)--67.0.42.232 (talk) 21:11, 26 February 2021 (UTC) has not attempted a description under this title, preferring the more logical alternative of placing it in the article titled Friendly Pair.

His description is better than the one here and so is the one in my article, http://upforthecount.com/math/mandrill.html

As copyright holder, I hereby grant Wikipedia a perpetual , non-exclusive , worldwide license to reproduce within Wikipedia under GFDL my descriptions of abundancy , friendlies of various sorts , and exclusive multiple from that article.

Use of the term kinship instead of abundancy is particularly inappropriate, and "club" seems questionable , although I can't immediately think of a better alternative.

I would tend to use "the 2-friendlies" or "the 7/3-friendlies", "friends of abundancy = 4" or "those of abundancy = 5/2".

I'm probably not the right one to rewrite this article, though I may eventually be able to do so.

Walter Nissen 2008-02-13 20:07 20:07, 13 February 2008 (UTC)

Please make this page more simple to understand! —Preceding unsigned comment added by 74.161.211.209 (talk) 15:50, 21 October 2007 (UTC)

Lead Paragraph
Is very confusing and seems to beat around the bush.. It doesn't help that the first example (6, 28, 496) are also all perfect numbers, which no explanation given. —Preceding unsigned comment added by CallipygianSchoolGirl (talk • contribs) 05:16, 14 April 2008 (UTC)


 * Does the edit help? PrimeHunter (talk) 14:47, 14 April 2008 (UTC)
 * It's a mild improvement, but the introduction still needs some work and a better example.--AaronRosenberg (talk) 17:19, 14 April 2008 (UTC)
 * What about ? (6, 28) is the smallest and simplest example, but not typical since the kinship is an integer. I pointed that out and made the smallest non-integer example later. PrimeHunter (talk) 22:35, 14 April 2008 (UTC)

Removal of "imaginary friends" pun
I see the "popular culture" section of this article has been removed without saying why. Although I have no vested interest in it one way or the other, I liked the pun. Of course, if removing the section improves this article, then I'm all for it. But the article doesn't seem any better now, without that section. Was the topic simply not notable?&mdash;GraemeMcRaetalk 16:01, 12 March 2009 (UTC)

Friendly pair notation
Do you have a reliable source for writing a friendly pair as {a, b}? I haven't seen it before. It's the notation for a set (mathematics) but a friendly pair is usually written (a, b), including in the reliable source http://mathworld.wolfram.com/FriendlyPair.html in the article. You need a better source to change away from that and you haven't given a source at all. (a, b) is also common notation for pairs in general, not just friendly pairs. PrimeHunter (talk) 09:37, 14 May 2014 (UTC)


 * One of the first things one learns in maths in high school is not to confuse a couple and a pair.
 * (1 ; 4) is a couple, and it is different from (4 ; 1)
 * {1 ; 4} is a pair, and it is equal to {4 ; 1}
 * In a maths article, writing a couple while calling it a pair is a bad idea . The best solution is to say  friendly couple . It would be consistent with what follows in the article : we have triplets (a ; b ; c) and lists (a ; b ; c ; d ; e).
 * --Nnemo (talk) 10:15, 14 May 2014 (UTC )
 * In a maths article, writing a couple while calling it a pair is a bad idea . The best solution is to say  friendly couple . It would be consistent with what follows in the article : we have triplets (a ; b ; c) and lists (a ; b ; c ; d ; e).
 * --Nnemo (talk) 10:15, 14 May 2014 (UTC )
 * --Nnemo (talk) 10:15, 14 May 2014 (UTC )
 * --Nnemo (talk) 10:15, 14 May 2014 (UTC )


 * Those semicolons look odd to me. Mathematical notation is not universal and the preferred notation at your high school doesn't trump reliable sources. Wikipedia uses common names and doesn't invent new names for existing concepts so we definitely shouldn't use your made up name "friendly couple". The Google search gives no relevant hits while  gives plenty, and they generally either write (a, b) or say "a and b" without specific notation. As a compromise I suggest we avoid the notation issue by saying "a and b". Whatever we do, it should be consistent within the article so if we change (6, 28) like you insist on then we should make the same change for (30, 140). PrimeHunter (talk) 20:53, 14 May 2014 (UTC)


 * OK for saying “a and b”. Or even “a, b”. --Nnemo (talk) 09:15, 15 May 2014 (UTC)


 * I have edited the article to say "a and b".[//en.wikipedia.org/w/index.php?title=Friendly_number&diff=608670287&oldid=608516686] PrimeHunter (talk) 10:31, 15 May 2014 (UTC)

Solitary numbers - 10, etc
It was recently added that 10 has no friend < 2,000,000,000. According to, 10 and some others have no friend < 10^30. Bubba73 You talkin' to me? 02:55, 22 December 2017 (UTC)

and friendly numbers are not the same as friendly pairs friendly pairs act like they are but their not the same — Preceding unsigned comment added by 67.0.42.232 (talk) 21:09, 26 February 2021 (UTC)

Friendly numbers in basic arithmetic
It looks like "friendly numbers" in common core are numbers that end in 5 and 0. I don't have a great reference for this other than this math lesson on YouTube, https://www.youtube.com/watch?v=G-79q7wk5ag. Parents may find this article and get even more confused because they're looking for the arithmetic definition. --TIB (talk) 02:25, 9 November 2023 (UTC)

Plagiarism and attempt to skirt removal of predatory publisher.
Citation [4] on this page leads to a ResearchGate writeup of a submission to the IOSR Journal of mathematics (a predatory / pay-to-play publisher) https://www.researchgate.net/publication/373980593_The_Form_of_The_Friendly_Number_of_10

Clicking through, we see that the author of this submission is one Sourav Mandal of Ramakrishna Mission Vivekananda University

Previously, this citation pointed directly to the IOSR Journal, but was rolled back because IOSR is not a reliable source. Checking the history of this Wikipedia article, you can see that both the original citation and the replacement were made by the IP address 14.139.215.81, which resolves directly to Vivekananda Educational & Research Institute West Bengal.

For this reason, I believe that Mr. Mandal has been editing this page with his own article in order to boost his mathematical reputation.

What's worse, however, is that if you read his journal submission linked above, it's almost a one-for-one plagiarism of a 2006 undergraduate project from Clarkson University in the US: https://lin-web.clarkson.edu/projects/cosi/fa2006/students/wardjm/lonenumber.pdf

I claim that Mr. Mandal plagiarized a 17 year old college project, submitted it to a scam journal, laundered the scam journal's link through the aggregator ResearchGate, and is personally seeding this Wikipedia page with references to his "work" for personal gain. 96.230.33.41 (talk) 16:28, 28 November 2023 (UTC)