How to Calculate the Year when you have the Month, Day, and Day-of-Week.
Calculate Steps 1 through 3 of the Day-of-Week technique, using 0 (zero) as the result in Step 2, the Full Year, then calculate Step 4, below, using the resulting (result) value from those steps.
Step 4 – Look up the known Day of the Week for the Target Date in the Day-of-Week Table. If the Result is greater than the value for the target Day-of-Week, add 7 to that target Day-of-Week value. Now subtract the Result from the adjusted Day-of-Week value. This result is the value for the target Year you are looking for in that year. Then, starting at one particular year, move forward one year at a time,* calculating the CY (full year) value for each year as you go along, until you find the first or additional matches with Target Value. If the Date is in Jan. or Feb, don’t forget to subtract one for full year values in leap years
For an example using January 11, 1988, click here (see parts I and IV only).
* There are three ways you can move forward from the start year to find the year with the value you are looking for. One way is the "crawl" method, in which you go forward one year at a time from the start year and calculate the year value for that year anew each and every new year until you find the value you are looking forward.
The second method is the "step forward" or "walk forward" method, where you move forward from the start year one year at a time adding 1 to the year value for each year but two for a leap year if the date you are looking for is after January or February, unless that year does not have the value you are looking for.
The third way is the "leap forward" or "jump forward" method where you add 4 years to the year and 5 to the year value, the extra value being for the extra day in a leap year (adjusting back by one of the year if the year you land on is a leap year and the month you are looking for is a January of February), and then stepping forward or backward one year and one value at a time to find the precise value you are looking for.
For the most sophisticated way to calculate the Year when you know the other three variables in a Date (the Day. Month and Day-of-Week), you can check out my entry on WikiHow (click here). However, even though this is actually the purest way to calculate this using the same basic process as the other three calculations, it is not very easy to remember or to do. Unlike the formula for the Day-of-Week where you only have to keep in your head the Date and some number between 0 and 6, you have more to hang onto in your head at one time. But also, I would not rely on WikiHow for this because others may come in and edit it and God only knows what will happen to the formula after. So instead of that more formal way to calculate the Year, above are the three ways I now recommend. I only developed he method I posted on WikiHow just to see what the simplest formula would look like, but it is too cumbersome to carry around in one's head.
Note: While you are still learning the technique, you could look up the values for the years in the Year Value Tables, but I suggest you not do that as they are not part of the process.
