Calendars
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Started by metmike - Sept. 22, 2018, 8:34 p.m.

1. When was our current Gregorian calendar adopted?

2. Who was it named after?

3. What calendar did it replace

4. Why do we have leap years?

5. How many other calendars are there around the world? Can you name some?

6. What day is it  today?

That last one is one of the questions they asked my 93 year old Dad on a recent cerebral functioning test. Today's date is probably on the bottom corner of your computer screen but how often do we temporarily forget the day of the week(especially during holiday weeks)?

If you're retired or really old and especially if living in an old folks home, it's probably getting harder and harder to tell the difference from each day to the next.

On the other hand, I have a trick that will allow you to tell the day of the week for any date of any year of any century!


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Re: Calendars
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By carlberky - Sept. 22, 2018, 9:27 p.m.
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" If you're retired or really old and especially if living in an old folks home,  it's probably getting harder and harder to tell the difference from each day to the next. "

I live in an extended care facility, but it's not hard at all. Every day is Saturday.

" On the other hand, I have a trick that will allow you to tell the day of the week  for any date of any year of any  century! "

I guess that means that the twin savant boys who could do that, just had a trick.


2. Who was it named after? Pope Gregory the some-thing-or-other.

4. Why do we have leap years? It takes the earth 365 days, 6 hours  to rotate around the Sun. Some Conservatives still believe the sun rotates around the Earth.

6 What day of the week is it ?  Saturday.

By metmike - Sept. 22, 2018, 9:58 p.m.
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"I live in an extended care facility, but it's not hard at all. Every day is Saturday."

"6 What day of the week is it ?  Saturday."

Carl,

Maybe you  just got lucky on #6?

...............since tomorrow will be Saturday, September 23, 2018, followed by Saturday, September 24, 2018. Then Saturday, September 25th, 26th and 27th (-:

Instead of the Gregorian Calendar, we should call it the Berky Calendar.

By carlberky - Sept. 22, 2018, 10:14 p.m.
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" Maybe you  just got lucky on #6? "

Mike, I wouldn't have answered #6 if I hadn't gotten lucky.  Gee,  I still have time to hit one of the Casinos ! 

By carlberky - Sept. 26, 2018, 9:16 a.m.
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" On the other hand, I have a trick that will allow you to tell the day of the week for any date of any year of any century! "

Mike, are you going to share ?

By metmike - Sept. 26, 2018, 9:23 a.m.
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Thanks for reminding me Carl.

I'll respond on that later today.

By metmike - Sept. 26, 2018, 1:46 p.m.
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Sorry for letting this slip by for  a few "days" but my assistant, Carl was here to save the "day" with a reminder.


Watch this incredible performance of a guy that can instantly calculate the day of the week, given the date:

Lightning calculation and other "mathemagic" | Arthur Benjamin

https://www.youtube.com/watch?v=M4vqr3_ROIk#t=7m50s


Carl,

Do you think that you and me could do the same thing, if only we knew his trick?

Yeah, right.........just give me a minute and the internet.


By metmike - Sept. 26, 2018, 1:56 p.m.
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1. When was our current Gregorian calendar adopted?

2. Who was it named after?

3. What calendar did it replace

4. Why do we have leap years?

5. How many other calendars are there around the world? Can you name some?

6. What day is it  today?


Carl correctly answered most of these questions already. It's still Saturday at his place too (-:


Pope Gregory introduced the current calendar over 400 years ago, that replaced the previous Julian Calendar, which is 13 days behind. That had replaced the Roman Calendar 2,000 years ago.

There are an incredibly large number of different calendars!

2018 in various calendars
Gregorian calendar2018
MMXVIII
Ab urbe condita2771
Armenian calendar1467
ԹՎ ՌՆԿԷ
Assyrian calendar6768
Bahá'í calendar174–175
Balinese saka calendar1939–1940
Bengali calendar1425
Berber calendar2968
British Regnal year66 Eliz. 2 – 67 Eliz. 2
Buddhist calendar2562
Burmese calendar1380
Byzantine calendar7526–7527
Chinese calendar丁酉(Fire Rooster)
4714 or 4654
    — to —
戊戌年 (Earth Dog)
4715 or 4655
Coptic calendar1734–1735
Discordian calendar3184
Ethiopian calendar2010–2011
Hebrew calendar5778–5779
Hindu calendars
 - Vikram Samvat2074–2075
 - Shaka Samvat1939–1940
 - Kali Yuga5118–5119
Holocene calendar12018
Igbo calendar1018–1019
Iranian calendar1396–1397
Islamic calendar1439–1440
Japanese calendarHeisei 30
(平成30年)
Javanese calendar1951–1952
Juche calendar107
Julian calendarGregorian minus 13 days
Korean calendar4351
Minguo calendarROC 107
民國107年
Nanakshahi calendar550
Thai solar calendar2561
Tibetan calendar阴火鸡年
(female Fire-Rooster)
2144 or 1763 or 991
    — to —
阳土狗年
(male Earth-Dog)
2145 or 1764 or 992
Unix time1514764800 – 1546300799
By metmike - Sept. 26, 2018, 2:08 p.m.
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So what's the trick to getting the day of the week from the date?


It's pretty easy for the last few and next few months:

The Easy (but Short Term) Mental Trick: Prepare Your Mind a Few Months Forward and Backward

https://www.reddit.com/r/LifeProTips/comments/l2z1p/quickly_figure_out_what_day_of_the_week_a_date/

The key to this is simple preparation and a bit of arithmetic. For any given month, all the multiples of 7 fall on the same day. I usually have memorized what day that is for the current month and the next few months. So October is a "friday month" and November is a "Monday month" and December is a "Wednesday month". You only have to memorize a new one every month.

Now when somebody says, "We should get together one Saturday. Say... December 12." you can snap back with "That's a Monday. Do you mean December 10?" All you have to do is find the nearest multiple of 7 and work from there. So when they ask about December 12, that's close to December 14 - which must be a Wednesday (since December 2011 is a Wednesday month).

If you have a few extra moments (like that useless time when other people are talking) you can even figure out future months if you don't know the day yet. So suppose you knew December was a Wednesday month, but didn't know January yet, you just add a few days based on how long December is (not how long January is). The number of days you add is the number of days in the known month - 28. December has 31 days, so add 3. So January is a Saturday month (+3), February is a Tuesday month (+3), March is a Wednesday Month (+1 because 2012 is a leap year), April is a Saturday Month (+3). So April 26 is a Thursday.

This sounds like a long explanation, but when you know the system, the calculations are super easy and it makes you look brilliant to people around you - great in work meetings.


It's more complicated if you want to go farther out but there is a formula:

http://gmmentalgym.blogspot.com/2011/03/day-of-week-for-any-date-revised.html#ndatebasics