# Talk:1935: 2018

This is easy! Don't factor it - just multiply by 25 and if that ends in two zeros, but not four zeros then it's a leap year, at least most of the time.....17:25, 29 December 2017 (UTC) 162.158.126.112 (talk) (please sign your comments with ~~~~)

This is easy! Don’t factor it - just convert it into a binary and look at the 2 least significant bits. If they are 00 the number is multiple of four. —172.69.33.35 17:37, 29 December 2017 (UTC)

This is easy! Don't factor it - just subtract 4 repeatedly. If you end up at 0, it's divisible. If you end up at 1, 2, or 3, it's not. -- 17:55, 29 December 2017 (UTC) 172.68.58.167 (talk) (please sign your comments with ~~~~)

The calculation of Christmas is trivial[citation needed] it's December 25th. Where as the calculation of Easter is complex ([1]). 172.68.133.18 18:03, 29 December 2017 (UTC)

Explanation of title text is incorrect: "The title text refers to calculating the date of Christmas; again, this is a trivial exercise, because Christmas is always December 25." Title text states 'day of Christmas', not 'date...'. The day changes each year and so does require calculation. 162.158.111.73 (talk) (please sign your comments with ~~~~)

Oops, my bad. Fixed. FlyingPiMonster (talk) 18:08, 29 December 2017 (UTC)

• I think you have it backwards. The title text is a reference to calculating the day (as in "date", not "day of week") of Easter. This is a non-trivial calculation (though one that modern computers can perform easily). On the other hand, the Christmas day is fixed. (There's no reason to believe that the joke was anything else.) - Mike Rosoft (talk) 19:13, 29 December 2017 (UTC)

I don't know who wrote the explanation, but... Are they having a bad day? 162.158.111.205 18:44, 29 December 2017 (UTC)

That was vandalism. I did a revert. --Dgbrt (talk) 19:06, 29 December 2017 (UTC)

Also, Megan understands that checking if a number divisible by 2 is easy 141.101.77.50 19:32, 29 December 2017 (UTC)
Theory for possible explanation

Didn't want to edit this in because I'm not sure- but the motivation for this uncharacteristic lack of mathematical rigor could have to do with the current trend of people being dismissive of science being able to predict things. Something that seems pretty obvious is made to look like a chance event that nobody can really predict ahead of time. -- Sirpent (talk) (please sign your comments with ~~~~)

This is easy! Don't factor it - just subtract 2000. Is 18 divisible by 4? If so, you're an idiot. 172.68.143.156 (talk) (please sign your comments with ~~~~)
The nonsense does look to me like a political discussion where one person uses "alternative facts". But in real life people get leap years "amusingly" wrong. Computer system designers for instance... one software tool I used passed into the year 2000 working correctly, but then it broke 2 months later because it thought 2000 wasn't a Gregorian calendar leap year, I guess because every 4th year is but every 100th year isn't. Every 400th year is, but, if the programmer just stopped at "every 4th is a leap year" then they'd have been fine until 2100. Robert Carnegie [email protected] 141.101.105.102 22:06, 29 December 2017 (UTC)

The joke in this might be that it might take some time to brute-force the prime factorisation of 2018 with a calculator as it’s 2*1009. (flx) 172.68.253.71 22:24, 29 December 2017 (UTC)