First, assign to each day of the Week a letter from A to G:
A, Sunday; B, Monday; C, Tuesday, D, Wednesday; E, Thursday;
F, Friday; G. Saturday
Then, add to the Year its Fourth Part, omitting Fractions, and also the Number 6. Divide the Sum by 7, and if there is no Remainder. then A is the Sunday Letter, but if any Number remains, the Letter that stands next to it in the Table below, is the Sunday Letter
Example : To find the Sunday or Domincal Letter for AD 2009
2009 divided by 4 = 502
502 + 6 = 508
508 divided by 7 = 72 remainder 4
4 = D
The Dominical Letter for AD 2009 is D; January 1 will be Thursday.
¶ In Bissextile or Leap Years, two Dominical Letters are assigned. The first is used for January and February, and the second thereafter. So, the Dominical Letters for 2008 were FE.
I had hoped to include a Table to find the Weekday of any date in the Year, but this blog apparently does not permit the format of such a Table. Likewise it has proved impossible to include the Calculations for finding the Date of Easter Day. [Incidentally, Easter will fall on April 12th in 2009.] For this reason the method of calculating the Golden Number is also not included. If a way is found, these shall appear. In the meantime, if you are interested in knowing these things, please inquire by comment at this blog.