3 ms·

I'm curious to understand what kind of life you live, or what you work with, when this information becomes so important that you need to be able to calculate it

I'm curious to understand what kind of life you live, or what you work with, when this information becomes so important that you need to be able to calculate it on whim, and fast too? Personally whenever someone asks me if I'm available on some date, or what I'm doing at a specific day or whatever, almost never does it matter what day of the week is, it's more about what things I have planned, and for that I have to open the calendar regardless as events beyond 1+ week horizon is quickly filled into my "Blank" cabinet in the brain. Not saying it isn't useful in the sense that avoiding these tiny hassles of "open calendar, find the date, look up what weekday" isn't worth it, I've unexplicitly trained myself to be ambidextrous for no real purpose except "that's neat", so I'd understand it, I'm mostly curious about actual usefulness of this in other's daily life, as seemingly my own looks very different from the ones where this'd be useful.

Hugsbox 2mo ago
I reckon it makes for a pretty neat party trick, I guess
rmunn 2mo ago
Like I said in answer to a similar question somewhere else in this thread, I rarely actually need to use this. But there have been times when it's come in handy, such as when I'm away from my computer and someone calls me on the phone to ask if I want to meet them for lunch on the 13th. I rarely remember my appointments by day of the month, but I do usually remember them by day of the week, i.e. I think "the 13th... (two seconds of mental math)... that's a Thursday. Right, I already made plans to have lunch with John Smith on Thursday next week." And then I can tell them "Sorry, I'm busy on the 13th, but I think I'm free on the 14th, let me check." And then I switch over to the calendar app, verify the 14th is free, and switch back to the phone app to confirm that I can meet them on Friday the 14th. That's how I end up using this most often. (And "most often" is still just every couple of months, mind). I still need to use the calendar app to record my appointments, but it sometimes lets me give people a "no, I'm busy that day, how about (other day)?" response with less of a conversational pause. So like you, I don't find it all that useful, but it still is nice to have from time to time. And I also just find it fun sometimes to know that the 13th of the month = Thursday without having to look anything up.
latexr 2mo ago
I’m not the person you asked and the technique I use is different (though also from an HN post). https://news.ycombinator.com/item?id=40464664 https://news.ycombinator.com/item?id=40464664 I think I may prefer that one, because it also allows me to figure out people’s birthdays. The key insight to making that one faster is to realise you can precalculate and memorise the year value for the year you’re currently in. Granted, having to memorise 12 magic numbers for the months maybe makes that one harder, but for some reason I immediately memorised the table upon looking at it once. To answer the question: I don’t really need to be able to do this, but I like it. It’s a fun, short, mental exercise. I even set up a daily reminder to quiz me on a random date every day. But it is practically useful, and it surprised me in how often I use it. Someone tells me of an event that’s going to be on a certain date and without breaking conversation I can figure out what day of the week it’ll be. I still think I’m fairly slow (I tend to double-check myself), but can still do it consistently slightly faster than someone who needs to take their phone out. Also, on a couple of occasions it has happened that as a group we needed to know a day of the week, someone checked it on their phone and made a mistake and I was able to catch it.
mananaysiempre 2mo ago
For me (not GP), this lives in the recreational-mathematics part of my brain rather than the useful-things part of my brain: John Conway called this invention of his the “Doomsday rule”[1] and I suppose the memorable name helps. But I admit having opened Calendrical Calculations[2] once or twice as well, so perhaps my idea of fun is skewed. [1] https://en.wikipedia.org/wiki/Doomsday_rule https://en.wikipedia.org/wiki/Doomsday_rule [2] https://en.wikipedia.org/wiki/Calendrical_Calculations https://en.wikipedia.org/wiki/Calendrical_Calculations
kjellsbells 2mo ago
latexr below makes a good point why: > without breaking conversation I can figure out what day of the week it’ll be Being able to maintain the flow of a conversation because you are able to do things in your head is incredibly useful social skill. It's like when you are talking at dinner with friends: the conversation goes back and forth and sideways, but as soon as someone pulls ouf a phone, the conversational dynamic changes.

Hugsbox 2mo ago

I reckon it makes for a pretty neat party trick, I guess

rmunn 2mo ago

Like I said in answer to a similar question somewhere else in this thread, I rarely actually need to use this. But there have been times when it's come in handy, such as when I'm away from my computer and someone calls me on the phone to ask if I want to meet them for lunch on the 13th. I rarely remember my appointments by day of the month, but I do usually remember them by day of the week, i.e. I think "the 13th... (two seconds of mental math)... that's a Thursday. Right, I already made plans to have lunch with John Smith on Thursday next week." And then I can tell them "Sorry, I'm busy on the 13th, but I think I'm free on the 14th, let me check." And then I switch over to the calendar app, verify the 14th is free, and switch back to the phone app to confirm that I can meet them on Friday the 14th. That's how I end up using this most often. (And "most often" is still just every couple of months, mind). I still need to use the calendar app to record my appointments, but it sometimes lets me give people a "no, I'm busy that day, how about (other day)?" response with less of a conversational pause. So like you, I don't find it all that useful, but it still is nice to have from time to time. And I also just find it fun sometimes to know that the 13th of the month = Thursday without having to look anything up.

latexr 2mo ago

I’m not the person you asked and the technique I use is different (though also from an HN post). https://news.ycombinator.com/item?id=40464664 https://news.ycombinator.com/item?id=40464664 I think I may prefer that one, because it also allows me to figure out people’s birthdays. The key insight to making that one faster is to realise you can precalculate and memorise the year value for the year you’re currently in. Granted, having to memorise 12 magic numbers for the months maybe makes that one harder, but for some reason I immediately memorised the table upon looking at it once. To answer the question: I don’t really need to be able to do this, but I like it. It’s a fun, short, mental exercise. I even set up a daily reminder to quiz me on a random date every day. But it is practically useful, and it surprised me in how often I use it. Someone tells me of an event that’s going to be on a certain date and without breaking conversation I can figure out what day of the week it’ll be. I still think I’m fairly slow (I tend to double-check myself), but can still do it consistently slightly faster than someone who needs to take their phone out. Also, on a couple of occasions it has happened that as a group we needed to know a day of the week, someone checked it on their phone and made a mistake and I was able to catch it.

mananaysiempre 2mo ago

For me (not GP), this lives in the recreational-mathematics part of my brain rather than the useful-things part of my brain: John Conway called this invention of his the “Doomsday rule”[1] and I suppose the memorable name helps. But I admit having opened Calendrical Calculations[2] once or twice as well, so perhaps my idea of fun is skewed. [1] https://en.wikipedia.org/wiki/Doomsday_rule https://en.wikipedia.org/wiki/Doomsday_rule [2] https://en.wikipedia.org/wiki/Calendrical_Calculations https://en.wikipedia.org/wiki/Calendrical_Calculations

kjellsbells 2mo ago

latexr below makes a good point why: > without breaking conversation I can figure out what day of the week it’ll be Being able to maintain the flow of a conversation because you are able to do things in your head is incredibly useful social skill. It's like when you are talking at dinner with friends: the conversation goes back and forth and sideways, but as soon as someone pulls ouf a phone, the conversational dynamic changes.