Talk:Leap year

Algorithm

The following pseudocode determines whether a year is a leap year or a common year in the Gregorian calendar (and in the proleptic Gregorian calendar before 1582). The year variable being tested is the integer representing the number of the year in the Gregorian calendar, and the tests are arranged to dispatch the most common cases first. Care should be taken in translating mathematical integer divisibility into specific programming languages.

if (year is not exactly divisible by 4) then (it is a common year)
else
if (year is not exactly divisible by 100) then (it is a leap year)
else
if (year is not exactly divisible by 400) then (it is a common year)
else (it is a leap year)

Excel

This algorithm translates into Excel like this, whereas year stands for the cell which refers to the input cell:

=IF(NOT((year/4=TRUNC(year/4)));"common year";IF(NOT((year/100=TRUNC(year/100)));"leap year";IF(NOT((year/400=TRUNC(year/400)));"common year";"leap year")))
or reversed, more simplified:
=IF((year/400=TRUNC(year/400));"leap year";IF((year/100=TRUNC(year/100));"common year";IF((year/4=TRUNC(year/4));"leap year";"common year"))

-- 23:17, 20 August 2015 31.151.83.20

Fine, but an Excel formula is not the sort of thing WP would ordinarily supply. The shape of the algorithm in pseudo-code is appropriate, but translations into specific languages generally not. -- Elphion (talk) 17:51, 26 August 2015 (UTC)

I have reverted bold replacement of the commonly used and readily understood term "century year" with the minimally (if at all after 1810) used coinage "centurial year". The reason given in the summary appears to be WP: original research. I cannot see any reasonable basis for change, even if some Victorian grammatical rule can be cited. 𝕁𝕄𝔽 (talk) 22:15, 16 August 2025 (UTC)

I agree with your revert. Meters (talk) 00:07, 17 August 2025 (UTC)

I don not agree.  Just because a term is "commonly used" doesn't mean such usage is correct.  "Century year” is incorrect terminology.  Any year that is exactly divisible by 100 is the last year of the century, not the first. "Centurial" is the correct adjective used to describe such a year.

If you want to get into a war over calendric and temporal terminology, I'm more than willing to oblige.  :)

Bigdumbdinosaur (talk) 06:16, 17 August 2025 (UTC)

Fwiw, the evidence for millennial year v. millennium year overwhelmingly favours the former. So I don't disagree in principle, but observe only that the term centurial year appears to have fallen out of use, so looks odd and therefore needs discussion to override WP:common name.

(The peak at 1800 was because that was the first occasion after the Calendar Act when a year evenly divisible by four was not a leap year. Looks like nobody cared in 1890 to 1910!) 𝕁𝕄𝔽 (talk) 09:42, 17 August 2025 (UTC)

On second thoughts, the equivalent of millennial year is centennial year. So that doesn't help. 𝕁𝕄𝔽 (talk) 13:35, 17 August 2025 (UTC)

Bigdumbdinosaur, we edit by consensus, not by what individual editors think is right. You are trying to change something, that change has been contested, so it is up to you to get consensus for your change. And stating that you will edit war over this is not likely to end well. Meters (talk) 10:00, 17 August 2025 (UTC)

Sorry if this looks like original research, but the rules do allow simple calculations. 365.2422 computes exactly as 365 + 1/4 - 1/128 + 1/80000. 128 is a multiple of 4 and 80,000 is a multiple of 128. Therefore using this system, every fourth year would be a leap year unless it is divisible by 128, but would be a leap year if divisible by 80,000. 365.2422 is probably an approximation, so it might end up being more complicated than this. 2A00:23C7:EE3F:7C01:DD2F:73EE:4BC9:E426 (talk) 09:21, 22 September 2025 (UTC)

365.2422 is an approximation too and varies over a long timescale. See False precision.

The current text documents the effect and accuracy of the Gregorian rule: it is not our function to propose anything better. 𝕁𝕄𝔽 (talk) 09:28, 22 September 2025 (UTC)

I recall from my younger years that at dances, women considered leap years times when they could ask men to dance (though men were not excluded from asking women to do so). Here are some Google Books links that support that. (They also refer to women inviting men to dances; but the dances I went to, at colleges, weren't one's where people invited others.) https://www.google.com/books?id=gkhFR-P4HagC&dq=%22leap+year%22+ask+dance&pg=RA4-PA98 https://books.google.com/books?id=pGB6EAAAQBAJ&pg=PT139 (5th paragraph), https://books.google.com/books?id=LElr_lnlEAIC&dq=%22to+the+leap+year%22&pg=RA2-PA681 ~2025-41294-19 (talk) 18:56, 29 December 2025 (UTC)