Editing Talk:1935: 2018
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This ''is'' easy! Sums of numbers that have 4 as a factor are all divisible by four. (I'll leave the proof of that as an exercise for the reader, but it's really trivial, though possibly non-intuitive.) This means that one can take a number apart and check the individual pieces. Now, any number that's a multiple of 100 is divisible by four (10 * 10 = 5² * 2²,) so one can essentially cut away the higher digits of a number, as they do not influence its divisibility with regard to 4. Now look at the first of the remaining digits. If that's odd, add 2 to the last digit. If the last digit is now divisible by four, the original number is divisble by four. [[User:Tibfulv|Tibfulv]] ([[User talk:Tibfulv|talk]]) 00:38, 30 December 2017 (UTC) | This ''is'' easy! Sums of numbers that have 4 as a factor are all divisible by four. (I'll leave the proof of that as an exercise for the reader, but it's really trivial, though possibly non-intuitive.) This means that one can take a number apart and check the individual pieces. Now, any number that's a multiple of 100 is divisible by four (10 * 10 = 5² * 2²,) so one can essentially cut away the higher digits of a number, as they do not influence its divisibility with regard to 4. Now look at the first of the remaining digits. If that's odd, add 2 to the last digit. If the last digit is now divisible by four, the original number is divisble by four. [[User:Tibfulv|Tibfulv]] ([[User talk:Tibfulv|talk]]) 00:38, 30 December 2017 (UTC) | ||
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The calculation of Christmas is trivial{{Citation needed}} it's December 25th. Where as the calculation of Easter is complex ([https://en.wikipedia.org/wiki/Computus]). [[Special:Contributions/172.68.133.18|172.68.133.18]] 18:03, 29 December 2017 (UTC) | The calculation of Christmas is trivial{{Citation needed}} it's December 25th. Where as the calculation of Easter is complex ([https://en.wikipedia.org/wiki/Computus]). [[Special:Contributions/172.68.133.18|172.68.133.18]] 18:03, 29 December 2017 (UTC) | ||
− | + | Calulsting the date of Christmas is actually non-trivial. It depends on your location. For example if you are in the US it's in December. If you are in Russia it's in January. If you are in Ukraine it's sortof both but not really. And if you are in Crimea, well, see one of the 2 previous sentences. --[[Special:Contributions/172.68.238.172|172.68.238.172]] 15:22, 30 December 2017 (UTC) | |
:Actually, it's December 25 on the old Julian calendar in Russia. It's just that Russia uses the Julian calendar for liturgical purposes and the Gregorian calendar for secular purposes. It's a bit schizophrenic. [[User:Billjefferys|Billjefferys]] ([[User talk:Billjefferys|talk]]) 19:40, 30 December 2017 (UTC) | :Actually, it's December 25 on the old Julian calendar in Russia. It's just that Russia uses the Julian calendar for liturgical purposes and the Gregorian calendar for secular purposes. It's a bit schizophrenic. [[User:Billjefferys|Billjefferys]] ([[User talk:Billjefferys|talk]]) 19:40, 30 December 2017 (UTC) | ||
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::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] [[Special:Contributions/141.101.105.102|141.101.105.102]] 22:06, 29 December 2017 (UTC) | ::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] [[Special:Contributions/141.101.105.102|141.101.105.102]] 22:06, 29 December 2017 (UTC) | ||
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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. Same holds true for 2017 which is prime. Therefore on might come to the conclusion that factorisation is hard already at this scale. (flx) [[Special:Contributions/172.68.253.71|172.68.253.71]] 22:24, 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. Same holds true for 2017 which is prime. Therefore on might come to the conclusion that factorisation is hard already at this scale. (flx) [[Special:Contributions/172.68.253.71|172.68.253.71]] 22:24, 29 December 2017 (UTC) | ||
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She can see that finding out if a number is divisible by 2 is easy, but for dividing by 4 it's a "50/50 chance", and really hard to calculate. IMHO the best joke in the comic but missing from the explanation. [[Special:Contributions/141.101.77.50|141.101.77.50]] 23:59, 29 December 2017 (UTC) | She can see that finding out if a number is divisible by 2 is easy, but for dividing by 4 it's a "50/50 chance", and really hard to calculate. IMHO the best joke in the comic but missing from the explanation. [[Special:Contributions/141.101.77.50|141.101.77.50]] 23:59, 29 December 2017 (UTC) | ||
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I think it's interesting that 2018 only has two factors, 2 and 1009. Maybe a trivia? | I think it's interesting that 2018 only has two factors, 2 and 1009. Maybe a trivia? | ||
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I think the joke in the title text is a play on the old joke that even though we know every year when Christmas falls, and every year we always say that we are going to begin saving or shopping in the months preceding Christmas we always get to December and are "surprised" that Christmas happens to be in December. Effectively Randall is suggesting that the reason we are surprised Christmas is in December is not due to forgetting but rather that we are "calculating" when the day is. Also related are Jokes about American Tax day (April 15th) or pretty much anything to do with procrastination. [[Special:Contributions/172.69.70.107|172.69.70.107]] 01:06, 31 December 2017 (UTC) Sam | I think the joke in the title text is a play on the old joke that even though we know every year when Christmas falls, and every year we always say that we are going to begin saving or shopping in the months preceding Christmas we always get to December and are "surprised" that Christmas happens to be in December. Effectively Randall is suggesting that the reason we are surprised Christmas is in December is not due to forgetting but rather that we are "calculating" when the day is. Also related are Jokes about American Tax day (April 15th) or pretty much anything to do with procrastination. [[Special:Contributions/172.69.70.107|172.69.70.107]] 01:06, 31 December 2017 (UTC) Sam | ||
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Here is some trivia! This comic is number 1935. In 83 more comics XKCD will reach number 2018. So sometime in the year 2018 we will have comic number 2018. Now go calculate what date that will happen ... and don't pull out your pocket slide rule [https://en.wikipedia.org/wiki/Slide_rule] to do the calculation. [[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 14:47, 1 January 2018 (UTC) | Here is some trivia! This comic is number 1935. In 83 more comics XKCD will reach number 2018. So sometime in the year 2018 we will have comic number 2018. Now go calculate what date that will happen ... and don't pull out your pocket slide rule [https://en.wikipedia.org/wiki/Slide_rule] to do the calculation. [[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 14:47, 1 January 2018 (UTC) | ||
Trivia "So we will have a comic named 2018 and a comic numbered 2018 both in the year 2018" is wrong: actually, comic named "2018" was published in the year 2017. [[Special:Contributions/195.62.179.66|195.62.179.66]] 07:23, 2 January 2018 (UTC) | Trivia "So we will have a comic named 2018 and a comic numbered 2018 both in the year 2018" is wrong: actually, comic named "2018" was published in the year 2017. [[Special:Contributions/195.62.179.66|195.62.179.66]] 07:23, 2 January 2018 (UTC) | ||
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