Published on 12, July, 2020
Some autistic people have a 'special skill' of being able to tell you what day of the week a particular date lands on. It is one of the autism clichés. But you can find patterns in the calendar that you can use to do this 'trick' quite quickly, even if you don't have an amazing memory or unusually fast mental maths. I thought some people might like to learn how to do it and impress people ;)
(I have tried to write it without maths terminology, although it is a bit simpler if you use a thing called modular arithmetic (click here).)
[A year is a leap year if it's a multiple of 4 but not a multiple of 100, or if it's a multiple of 400. E.g. 1900 isn't, 1904 is, 2000 is because it's 5*400]
If 1st January is a Monday in a particular year, call this year 'special'.
Some of the 'special' years are 1912, 1940, 1968, 1996, 2024... (gaps of 28 years)
(5 years from these) 1917, 1945, 1973, 2001, 2029...
(6 years on again) 1923, 1951, 1979, 2007,2035...
(and 11 years on again) 1934, 1962, 1990, 2018, 2046...
[This pattern will change after 2100 because 2100 is not a leap year, as it's a multiple of 4 and a multiple of 100 but not a multiple of 400.]
Every year, the day of the week of a certain date moves on by 1 day, or 2 days if you go past a leap-day. E.g 12th July is Monday this year so 12th July will be a Tuesday next year.
Example: Day of the week of 15th September 2000
First work out which day 1st January is on. 1st January 2000 is 4 years on from Monday 1st January 1996, and we go past 1 leap day (Feb 29th 1996) so the day of the week moves on by 5 - that's 1 for each year, and 1 extra for the leap day. So it's a Saturday.
Then work out how much the day of the week moves on for the 1st of the month. In a normal year we would have 0,3,3,6,1,4,6,2,5,0,3,5 (for January through to December). If it's a leap year and the date is in March or later, you need to add an extra 1 day. So the 1st Sep 2000 is 5 days moved on from 1st Jan 2000, plus 1 day because of Feb 29th, it's 6 days moved on from 1st Jan 2000.
Then we move on a further 14 days to get from 1st Sep to 15th Sep, which is the same as moving 0 days on because 14 days is 2 whole weeks.
So the answer is Saturday plus 6 days, which is Friday. This is right, you can check it with Google.
Spam comment.
Wow, my memory doesn’t even allow me remember all these hacks you posted, numbers always were my trouble, lol. I barely made it in school and now it’s such a relief that I don’t have to do this anymore! I use another hack for memorizing important events. I print paper calendars at [remove by mod] (just like its simple design and enough space for writing), write down all the meetings or celebrations and stuff. Then I put it on the wall in the place I often look at. Visual memory is one of the most strong, so after seeing it 4 or 5 times I can easily say what is when
Untoward said:I also have a photographic memory for the locations of objects.
That's probably the most useful thing ever - my memory tricks are of no use to anyone except me - and even then only in certain circumstances.
How do you see things in your mind? Do you see the object and then zoom out or the other way around - or is it just a huge database in your mind?
people like u where used to catch many N_azi camp nasties ---- they never forgot their faces many years later they where recognised and found.
Have you ever thought of using that talent? The Met Police recruit super recognisers as CCTV searchers. Looking to see if sometime they're looking for appears on any CCTV footage they may have. I don’t think it's a full time job, just as and when needed.
Plastic said:I have great difficulty recognising faces - they change and move and have different hair styles or makeup - too many variables.
I'm actually a super-recogniser for faces (and so is my dad). I remember every face I've seen. When watching TV show or movies I can tell you which lesser known actor it is, and which episode of a TV show from 20 years ago I remember him/her from, even if the hair is completely different or they have aged drastically.
I used to act with recognition when seeing someone that I met once before years ago, but I learnt that other people do not remember and they do not like it so now I keep my mouth shut when I recognise people.
I also have a photographic memory for the locations of objects. I can't do your magazine thing, it's more about physical locations and orientations in the real world. I can tell you exactly where every object I've ever owned is. It just happens without any effort. Growing up I thought everyone could, but the amount of times people lose things eventually taught me that maybe it's a special thing (but the fact the memory palace is a mechanism for remembering things suggests maybe everyone finds locations easier to remember).
When I lived at home my parents always used me to find things, and continued to do so for the first couple of years after I moved out. They would phone me up to ask where something is and I would tell them something like "it's in the second draw down in the garage, underneath a user manual for the drill". I could even tell the orientation of it - and I know whenever someone has used something because it will be put back in a slightly different position.
Impressive. I barely know what day it is today! Lol! Maths (and science and tech) used to be my thing before I developed a chronic condition that screwed my memory up, now I sometimes struggle with 2 digit additions! Lol! I used to know someone, who wasn't autistic, who could do that. It would take him around 10 seconds to tell you the day, and he was never wrong. Always amazed me.
likewise
u're impressive
Luckily if you do the trick with people's birth dates, they are very unlikely to be born before 1582 so this hasn't come up yet ;) But the Julian calendar, used before 1582, has a simpler pattern of leap years so the trick would be less complicated. Although, I just read that before the Julian calendar was introduced the calendar was a complete mess so even the Romans at the time were confused about what day it was. Apparently the era was known as 'the years of confusion' haha.
Do you take account of the fact that the Gregorian calendar was introduced in 1582?
I see flavours as shapes & colours - difficult to describe - a good burger with lots of complimentary flavours is like a sun-rise. Pizzas are spiky. Chinese food is smooth and shiny.
BassFace said: solving a Rubik's Cube blindfolded
What? How?
A Rubik Cube leaves me in knots. I was hopeless at them.
I have another party trick of solving a Rubik's Cube blindfolded. But I learnt the method from the internet, I couldn't figure that one out by myself.
Wow, I am impressed that you could remember an entire stores list. Just wondering, do you have synaesthesia with letters/numbers?
Yeah I lose track of the days when I'm on holiday, and lose track of am/pm if I take a nap when I'm burnt out...
I don't have a particularly good memory for dates, but I like finding patterns in the calendar.
I know that I was born on a Monday, and work from there.
I often don't even know what day it is today.
I wake up and have no idea if it's morning or evening, bedroom clock shows 8, but is it am or pm? I'm in bed in my day clothes. I just remember I went to bed at around 7:30pm, have I slept 30minutes or 12 hours?
Today feels like Sunday although I'm certain it's Monday.
That's very interesting.
I wonder how many other different savants we have on here.
I have great difficulty recognising faces - they change and move and have different hair styles or makeup - too many variables.
I have a savant presentation for 'things I've seen' - a photographic memory - I can do tricks like give me a pile of magazines, let me go through them and than show me a single picture - I'll tell you which magazine, which page and location on the page.
I worked in a place where I had to order lots of things from stores - it was easier to just memorise the whole stores list - about 5500 different 10-digit alpha-numeric codes.
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Anyone else got a party trick?