Scott Cram's tutorial

Scott Cram posted a free tutorial on how to quickly create a month calendar for months and years as far back as 45 B.C.! 

I'm a great admirer of Scott’s very inspiring blog.

http://gmmentalgym.blogspot.com/2014/05/......#cmintro

His tutorial turns out that the following 3 approaches, when careful attention is paid to the mathematics, come together to form a simple, yet powerful, approach to calendar calculation:

• E. Rogent's and W.W. Durbin's “How to find the day of the week on which any particular date falls”

• Bob Goddard's "First Sunday Doomsday Algorithm":

• Scott Cram’s own "Day One":

I cite the following sources regarding this approaches in my book "Encyclopedia of Day of Week Calculation":
[6.2.1] Martin Eisele: "Kalendertagsberechnung", privates Manuskript, 2005
[6.2.2] Michael K. Walters: "An Improved Doomsday Algorithm", Blogspot blog, 2008
http://easydoomsday.blogspot.com/; (25.03.2011)
[6.2.3] Robert Goddard: "Learn the First Sunday Doomsday Algorithm", Blogspot blog, 2009
http://firstsundaydoomsday.blogspot.com/; (25.03.2011)
[6.2.4] E. Rogent, W. W. Durbin: "How to find the day of the week on which any particular date falls", The Linking Ring, Vol. 6“; August 1927. 
[6.2.5] YingKing Yu: "A Perpetual Calendar in Your Head", Blogspot blog, 2010
http://improvedddabyykyu.blogspot.com/2010/09/perpetual-calendar-in-your-head-by-dr.html; (25.03.2011)
[6.2.6] Chamberlain Fong, Michael K. Walters: "Methods for Accelerating Conway's Doomsday
Algorithm (part 2)", Blogspot blog, 2010
http://arxiv.org/ftp/arxiv/papers/1010/1010.0765. pdf (25.03.2011)

[8.3.1] Robert Goddard: "Learn the First Sunday Doomsday Algorithm", Blogspot blog, 2009
http://firstsundaydoomsday.blogspot.com/; (25.03.2011)
[8.3.2] Scott Cram: „Day One“; E-Book, Lybrary.com, 2012

[8.3.1] Robert Goddard: "Learn the First Sunday Doomsday Algorithm", Blogspot blog, 2009
http://firstsundaydoomsday.blogspot.com/; (25.03.2011)

If you are dealing only with Gregorian calendar years from 1900-2099 I recommend my old “ki-approach”

(see https://www.blogger.com/comment.g?blogID=3985237709515317836&postID=6187795269912123249 )

for the Doomsdays
“Divide last leap year by 2, subtract the lost years, calculate modulo 7 and find the complement to 10” or 

for the year key
“Divide last leap year by 2, subtract the lost years, calculate modulo 7 and find the complement to 7.” 

BTW: Jackerz comment "The proposal is a variant of YingKing's method." is not correct. It is a variant of Durbin's approach frome 1927. YingKing didn`t know the sources (as typical for most mathematicians).

No century keys are needed. 

Please use only years since 1900!

Month keys are:

033-614-625-035 (common years)
623-614-625-035 (leap years)

___________________________________________________
Example 1
1975 ==> 75=72+3
72/2 ==> 36 - 3 ==> 33 ==> 5 to 10 ==> 5 ==> Doomsday is a Friday
or
72/2 ==> 36 - 3 ==> 33 ==> 5 to 7 ==> 2 ==> year key is 2.

Example 2
April 7th, 1982 ==> 82=80+2
80/2 ==> 40 - 2 ==> 38 ==> 3 to 10 ==> 7 ==> Doomsday is a Sunday
or
80/2 ==> 40 - 2 ==> 38 ==> 3 to 7 ==> 4 ==> year key is 4.
4/7/1982 ==> 6+7+4 ==> 17 ==> 3 ==> Wednesday

Example 3
Febrary 29th, 1992 ==> 92=92+0 (leap year!)
92/2 ==> 46 - 0 ==> 46 ==> 4 to 10 ==> 6 ==> Doomsday is a Friday
or
92/2 ==> 46 - 0 ==> 46 ==> 4 to 7 ==> 3 ==> year key is 3.
2/29/1992 ==> 2+29+3 ==> 34 ==> 6 ==> Saturday

Example 4
2014 ==> 114=112+2
112/2 ==> 56 - 2 ==> 54 ==> 5 to 10 ==> 5 ==> Doomsday is a Friday
or
112/2 ==> 56 - 2 ==> 54 ==> 5 to 7 ==> 2 ==> year key is 2.