Talk:1

Semi-protected edit request on 17 January 2025

Do roman numbers I=1 Busserler (talk) 08:13, 17 January 2025 (UTC)

 Not done: Your request is not clear, but the the Roman numeral is already in the infobox Polyamorph (talk) 08:40, 17 January 2025 (UTC)

Linebreak problem

This article has many occurrences of expressions like: (<math>1!=1</math>). The problem is that the browser may put a linebreak between the closing 'math' tag and the right paren. Perhaps these should be <math>(1!=1)</math> ... I'm not sure, and hope there is a definitive answer. Imaginatorium (talk) 15:16, 29 December 2025 (UTC)

@Imaginatorium. How about not to use the parentheses at all? Dedhert.Jr (talk) 07:16, 30 December 2025 (UTC)

Another property...

1 is one of 4 numbers that satisfy the relationship "n! is a number of n decimal digits". The others are 22, 23 and 24. ~2025-43833-86 (talk) 15:50, 30 December 2025 (UTC)

Not sure I can understand this property. Can you elaborate? Dedhert.Jr (talk) 09:56, 31 December 2025 (UTC)

1! is 1 digits long. 22! is 22 digits long 23! is 23 digits long. 24! is 24 digits long. Wolfram Alpha (and a bit of common sense for 1!) agrees with the temporary account editor: 22!, 23!, 24!. I found this by googling "n! has n digits" but I'm not smart enough to understand what it says :( Source does look reliable though. --not-cheesewhisk3rs ≽^•⩊•^≼ ∫ (pester) 12:38, 8 February 2026 (UTC)

WP:CALC almost applies, but it is also necessary to note that 25! happens to have more than 25 digits and, for n>25, n! will have more than n digits by induction because n! > (n-1)! × 10. That's bordering on not very original research and might need a source. However, I'm not sure this is an important property of the number 1, which is an exceptional case for many formulae. It might make a more relevant entry for 22 (number) or 24 (number). Certes (talk) 18:52, 8 February 2026 (UTC)

If this is added to the other numbers where it applies, it would also be worth mentioning that 1 is also a number with this property. Though I do agree this isn't very important for 1, so doesn't need inclusion in this article. --not-cheesewhisk3rs ≽^•⩊•^≼ ∫ (pester) 20:24, 8 February 2026 (UTC)

@Dedhert.Jr ~2026-23310-07 (talk) 01:37, 16 April 2026 (UTC)

As long as there are published, reliable sources ... Dedhert.Jr (talk) 01:39, 16 April 2026 (UTC)

Yeah. It's an interesting factoid about those four numbers, but as a misc. factoid I don't think it deserves more than a brief mention.

A non-RS source (appears to be crowd sourced) is https://proofwiki.org/wiki/Numbers_Equal_to_Number_of_Digits_in_Factorial Maybe there's a better source? Mr. Swordfish (talk) 13:15, 16 April 2026 (UTC)

As I stated in my comment below, it is already stated in the article that 1 is its own factorial. I don't agree that it is sufficiently relevant to include other numbers here. Polyamorph (talk) 16:34, 16 April 2026 (UTC)

The article already states that 1 is its own factorial. I agree with Certes that it may be relevant to include in the other numbers that have this property (if not already there, I haven't looked). Polyamorph (talk) 20:14, 8 February 2026 (UTC)

I think this is precisely the sort of property that does not belong. I think (shaky OR) that 4 is the only (decimal) number n whose factorial n! does not have length n in any base. I do not think that fact belongs in 4 either, though it seems obviously more notable than the OP's fact. Imaginatorium (talk) 17:27, 16 April 2026 (UTC)