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The Magic Cafe Forum Index » » Magical equations » » Which day, but for 1900-2000?? (0 Likes) Printer Friendly Version

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hcs
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Quote:
On 2010-05-02 09:36, TomasB wrote:
I see, hcs. The "div" confused me as it's much more common to write "mod".

I'm very sorry. Of course mod is much more common then div.
Quote:
So if I bake the lonely 6 into the M code I get
M=6-2-2, 5-0-3, 5-1-4, 6-2-4
Weekday = (y + floor(y/4) - 2*Ymod4 + M + D)mod7
Is there a good way to remake the "y + floor(y/4)" the same way? Anyway, the formula looks so much simpler now. Thanks!
/Tomas

Here is a simple way invented by Lewis Caroll in 1887.
the "Method of Dozens" is very common:

y' = [y int 12 + y mod 12 + (y mod 12) int 4]mod 7.
Formula looks terrible but it is very simple.


Example
1929
y' = [29int12 + 29 mod 12 + (29 mod 12)int4] mod7
(29/12 ==> 2 remainder 5 and 5 int 4 ==> 1)
y' = (2 + 5 + 1)7 = 8 ==> 1

(„29 includes 2 dozens and remainder 5,
remainder 5 includes 1 leap year")

(There are still other simple calculation methods).
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hcs
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On 2010-05-01 16:07, hcs wrote:
Quote:
On 2010-04-28 15:20, Scott Cram wrote:
Here's a couple of more interesting alternative calendar approaches:

On what day of the week were you born?: This one features an interesting approach using keys for decades!

Abel Stroock's formula: This formula uses only 2 numbers. The catch? You have to know how far into the year a given date is, such as April 15th being the 105th day of the year (which can be learned in Thomas Harrington's Magic of Memory).

Abel Strook's formula is very interesting. It is a variation of formula, published in 1909 by the russian mathematician J.I. Perelman, in the russian Journal "Priroda I Lyudi (nature and people), 1909, No. 22
cited in Butkevich/Selikson "Ewige Kalender (perpetual calendars)", Leipzig, 1987, p.91
(or in my encyclopedia "2.5. unechte Kennzahlmethoden (unreal key number methods), 2.5.2. "Tag I'm Jahr"-Methode ("day in year" method)):
W = (Y + Y int 4 + H int 4 – H + D – 1)div 7

Differences in formula caused by different key numbers for day of the week and that Perelman used.

As I am reading now in my own book Abel Stroock's formula was published in the same form by the Russian S. Drozdov in 1954 in "kratky astronomichesky kalendar na 1955 g. (short astronomical calendar for year 1955).
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hcs
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I only have seen
Quote:
On 2010-05-02 09:36, TomasB wrote:
I see, hcs. The "div" confused me as it's much more common to write "mod".

div means "floor" or "int" not "mod".
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PatBee67
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Does anyone know how Zufall's method compares to Dominic O'Brien's method as published in "How To Develop A Perfect Memory" ?
Scott Cram
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PatBee67, The formula in both is the same, as it pretty much has to be.

The main differences are:

1) The particular mnemonic codes for letter that is used (Dominic uses 0=O, 1=A, etc., while Zufall uses the standard phonetic alphabet, 0=S, 1=T/D, etc.).

2) Zufall has you memorize the year codes as words/phrases, while Dominic has you put groups of years in their appropriate metal "rooms".

3) Zufall uses 0 for Sunday, up to 6 for Saturday. Dominic uses 1 for Sunday, up to 6 for Friday and 0 for Saturday. This last one doesn't really matter, assuming your other key numbers are adjusted appropriately.

BTW, regardless of which system you use, there's some great mp3 Day For Any Date training files available for free. They're available in both Day/Month/Year order and in Month/Day/Year order, and feature pauses of various lengths from 30 seconds all the way down to 3 seconds.
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Thank you Scott for your clear explanation of the differences.

I do have Dominic O'Brien's e-book but did change the mnemonics for the numbers, as appears now just like Zufall, to the phonetic alphabet that I've been using since long.

Do you see any advantage to using the words/phrases for the years as opposed to learning which number (person) is situated in which particular mental room? I assume that Zufall has a method that groups those words?

Rgds,
Patrick
Scott Cram
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In Zufall's method, the years aren't really "grouped". The last 2 digits of each year (59, for example, from 1959) are linked with the year code (3 for 1959) through the use of a word ("album" translates to 593, indicating that the key for 1959 is 3).

You're basically remembering 100 words, made from the last 2 digits of the year plus the digit for the year code.
hcs
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In my book "Encyclopedia of weekday calculation" I explain a more modern solution for linking the year's digit keyword with year. I'm IMHO the first with a SIMPLE mental extension for the full 400 year cycle (chapter 8.3).

It is necessary to learn the 100 coded words for the 2 year digits only but not twice for year digits and years as Zufall explains!
http://www.lybrary.com/kalender-kopf-gral-p-35993.html
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hcs
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BTW I've presented the opening show on the Mental Calculation World Cup in June 2010. Freddies Reyes Hernadez from Cuba is the new world record holder in weekday calculation with 74 calculations in one minute and 20 calculations (one century) in 13,47 sec. (see photo).

...I know Freddies personal records. they are much higher!

Click here to view attached image.
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hcs
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Here comes of photo of Freddies and me on Mental Calculation World Cup in Magdeburg, Germany.
The "other all" winner was a young indian girl.

Click here to view attached image.
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TomasB
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WOW! I didn't even have time to read most of the dates. Supernatural. I demand that he gets the million dollars from JREF.

/Tomas
stanalger
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Hernandez is fast, but he's no longer the fastest.
Jan Van Koningsveld from Germany is the new Mental Calendar World Recold Holder with 78 correct dates in one minute.
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Those learning Day for Any Date may be interested in the new improved version of my free interactive practice tool, which now includes solution times.

http://www.mindmagician.org/daydate.aspx

Mike
hcs
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On 2010-10-07 17:01, stanalger wrote:
Hernandez is fast, but he's no longer the fastest.
Jan Van Koningsveld from Germany is the new Mental Calendar World Recold Holder with 78 correct dates in one minute.

Here is a photo. On the left is Jan van Konigsveld, on the right side is the German Robin Wirsing. Robin is also able to do more the one calculation per second.

Click here to view attached image.
Melencolia I - Magic Squares for the Mental Entertainer * Smart Methods for 4x4, 5x5 and 6x6 Magic Squares * 180 A4-pages * version 3.51
hcs
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Sorry: Jan van Koningsveld and Robin Wersig!
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Hi everybody. I've just found this forum. I am not as fast as these men, but I found a new method for the calendar. I used the "method" word instead of formula, because it has no number or it needs no calculation such as addition, substraction, multiplication or the remainder. I am preparing a document for it, but it needs some corrections. When it will be finished, I want to publish it by a Creative Commons license.

PS. I've sent already the drafts to the mentioned Super Calendar Men.
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Quote:
On 2010-10-07 17:01, stanalger wrote:
Hernandez is fast, but he's no longer the fastest.
Jan Van Koningsveld from Germany is the new Mental Calendar World Recold Holder with 78 correct dates in one minute.


Here's a video of Jan Van Koningsveld'......ormance!

Quote:
On 2010-11-05 14:05, ssakgul wrote:
Hi everybody. I've just found this forum. I am not as fast as these men, but I found a new method for the calendar. I used the "method" word instead of formula, because it has no number or it needs no calculation such as addition, substraction, multiplication or the remainder. I am preparing a document for it, but it needs some corrections. When it will be finished, I want to publish it by a Creative Commons license.

PS. I've sent already the drafts to the mentioned Super Calendar Men.


Thank you for this!

I've found this document posted over at Yahoo's MentalCalculation Group's files section (listed as CCWN.7z). Once you download it and unpack it, you'll have a password-protected PDF, and instructions on how to contact the author for the password.
stanalger
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Yusnier Viera Romero has set some new records:
http://www.recordholders.org/en/records/dates.html
93 dates in 1 minute!
Santiago
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I've learned this algorithm and I think it's great. I love it because it's really easy.

It's called Doomsday Algorithm, and as you'll find, it gives the day of the week for any date (and you can do it in your head).

I hope this helps you Smile

By the way

Quote:
On 2010-11-05 14:05, ssakgul wrote:
Hi everybody. I've just found this forum. I am not as fast as these men, but I found a new method for the calendar. I used the "method" word instead of formula, because it has no number or it needs no calculation such as addition, substraction, multiplication or the remainder. I am preparing a document for it, but it needs some corrections. When it will be finished, I want to publish it by a Creative Commons license.

PS. I've sent already the drafts to the mentioned Super Calendar Men.


This sounds really great! I'll be waiting Smile

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