Memorizing the Calendar
Bill Long 8/29/06
Not as Difficult as You Might Think
As I have been reading more and more on "savants" (they used to be called "idiot savants," where the word "idiot" emphasized their unique ability in one area, but for obvious reasons this term has mostly disappeared), I realize that savant capabilities are normally in only a few areas, such as drawing, musical performance, memory feats, etc. One of the areas where many savants have been said to perform exceptionally well is in calendar memorization. In short, they can tell you, almost instantaneously, on which day of the week any date from the past two or three centuries occurred. Kim Peek, for example, has this ability and managed to "wow" Dustin Hoffman and his friends when he met them prior to the making of the award-winning movie Rain Man, in which the character of Raymond Babbit was modeled on Peek. Peek, born in 1951, is increasingly receiving media attention; a short biography of Kim by his father, Fran Peek, appeared in 1996.
I don't know if I possess savant characteristics, but I wanted to see if I could develop a method which would be able to perform this "savant-like" activity. That is, I wanted to see if this fairly common savant characteristic was really as difficult to attain as it appeared to be at first. So, what I have done over the past few weeks, especially when I am driving in my car or taking rather long trips where concentrated reading is difficult, is to develop a method to memorize the historical calendar. Here it is.
Using an Anchor Date
The key to learning how to memorize the calendar is to know on which day of the week the same date falls each year. For example, I picked my birthday (May 15) as the anchor date for me. I knew on what date it fell in 2006 (Monday) and 2005 (Sunday), and then I recalled that the way dates work is that the advance one day in the week per year except when you have a leap year, and then they advance two days. Thus, we have the following dates for my birthday in the past 8 years.
You can (and I have) made a 107 year chart, listing my birthday for each year from 1900 to 2006. Then, you realize that the calendar repeats itself every 28 years, so that the calendar for 2006 is the same as 1978, which is the same as 1940, which is the same as 1912. Then, you realize that the day in every four year cycle, beginning for me in 1900 is five days ahead of the day of the next four year cycle. What this means is that May 15, 1900, a Tuesday (which is the same day as May 15, 1928; May 15, 1956; May 15, 1984; May 15, 2012), will be five days "ahead" of May 15, 1904, which is a Sunday. Then, May 15, 1912 will be a Friday; May 15, 1916 a Monday; May 15, 1920 a Saturday; May 15, 1928 a Thursday and, finally, May 15, 1928 a Tuesday again. Note that in the cycle of 28 years each of the seven days of the week rotates to become the day of May 15 in each successive leap year. The pattern is as follows:
Tuesday-- 1900. Then, add five days
Sunday--1904. Then, add five days
Friday--1908. Then, add five days
Wednesday--1912. Then, add five days
Monday--1916. Then, add five days
Saturday--1920. Then, add five days
So now we are filling things in pretty rapidly. I even developed a little song-jingle to have me learn in which order the seven days of the week appear each leap year, so that we have Tuesday, Sunday, Friday, Wednesday, Monday, Saturday, Thursday... Once you have mastered the framework of the 28-year cycle, you can fill in the other years in between without much difficulty. Then, you just "repeat" the 28-year cycle for the other four 28 year periods in the time I am memorizing. But this is just the beginning.
Calcuating the Months
So, here is how I know when my birthday was at any time in the last century. If I said, "May 15, 1933," I would immediately go to 1932, which is in the second "cylce" of 28 years, then realize that May 15, 1932 is a Sunday (because May 15, 1904 was a Sunday) and then I only have to move up one day as 1932 turns to 1933--and realize that May 15, 1933 is, in fact, a Monday. I wrote this out step-by-step, but it really is almost instantaneous. Another example. What day of the week was May 15, 1959? Well, it would be a Friday. I did it instantaneously, because I realized that it would be in the third 28 year-cycle of years, but in the first four-year block. May 15, 1956 (which is the same day as May 15, 1900) was a Tuesday. Therefore, march forward three days (1957-59) and you have Friday. Bingo.
Well, this explains how I can easily calculate my birthday. There are 364 other days of the year. How can calculating those days be easy? The next essay shows you how.
Copyright © 2004-2008 William R. Long