“The following formula - named Zeller’s Rule - allows you to calculate a day of the week for any date:
F = k + [(13 x m-1)/5] + D + [D/4] + [C/4] - 2 x C
k is the day of the month. Let’s use January 27, 2024 as an example. For this date, k = 27.
m is the month number. Months have to be counted specially: March is 1, April is 2, and so on to February, which is 12 (this makes the formula simpler, because on leap years February 29 is counted as the last day of the year). Because of this rule, January and February are always counted as the 11th and 12th months of the previous year. In our example, m = 11.
D is the last two digits of the year. Because of the month numbering, D = 23 in our example, even though we are using a date from 2024.
C stands for century: it’s the first two digits of the year. In our case, C = 20.
Now let’s substitute our example numbers into the formula:
F = k + [(13 x m-1)/5] + D + [D/4] + [C/4] - 2 x C
= 27 + [(13 x 11-1)/5] + 23 + [23/4] + [20/4] - 2 x 20
= 27 + [28.4] + 23 + [5.75] + [5] - 40
[drop every number after the decimal point]
= 27 + 28 + 23 + 5 + 5 - 40 = 48.
Once we have found F, we divide it by 7 and take the remainder (if the remainder is negative, add 7). A remainder of 0 corresponds to Sunday, 1 means Monday, etc. For our example, 48 / 7 = 6, remainder 6, so January 27, 2024 will be a Saturday.”
[or use a perpetual calendar table]
This and much, much more puzzles, illusions, and mathematical tricks at the Archimedes’ Lab
—–
Tuesdays with Morrie (by Mitch Albom) is a story about a young sportswriter and his old Sociology professor in college (who’s dying from Lou Gehrig’s disease) and their final lessons about some of the more important things in life. Some might remember the TV mini-series based on the book, with Jack Lemon and Hank Azaria (he does look like the author). The book is short and very easy to read, yet the lessons learned are valuable and profound. I highly recommend it.
—–
Scientific American: Name That Tune — Music lovers use cell phones to identify songs
Shoot, this is yet another one of my start-up idea being implemented by someone else :(
Lost chance to become a multi-millionare aside, the fact that this type of seemingly simple problem for human is difficult for the computer is intriguing. (For example, when people know a song, they can quickly recognize it, with much error tolerance) It leads me to believe that we either have the wrong tool (bad computer design), wrong approach (bad software design), or simply that AI is too difficult of a problem to solve.
—–
Should you aim for the back wall or the water??? The answer and more answers to life’s interesting questions at The Straight Dope
—–
New $20 bill was introduced today. Click here to see an “interactive bill” which shows the new features. I found some interesting facts about Money from the site. For example:
- Have you ever wondered how many times you could fold a piece of currency before it would tear? About 4,000 double folds (first forward and then backwards) are required before a note will tear.
- 95% of the notes printed each year are used to replace notes already in circulation. 45% of the notes printed are $1 notes.
- The origin of the “$” sign has been variously accounted for, however, the most widely accepted explanation is that the symbol is the result of evolution, independently in different places, of the Mexican or Spanish “P’s” for pesos, or piastres, or pieces of eight. (I heard it comes from writing “U” and “S” overlapped. “$” used to have 2 veritical lines, then people started omitting one).
Still, no mention of “666″ or “illuminati” however :)
—–
An astonishing 20,000 Canadians declared themselves to be followers of the religion of Jedi, the guardians of peace and justice in the Star Wars flicks… In the U.K., … there are more Jedis than Jews. Nearly 400,000 people identified themselves as Jedi in the 2001 census. Only 260,000 said they were Jewish. The Jedis seemed to be concentrated in England and Wales.
Read full article here . This is a serious threats to those Scientologists! ;)
May the force be with you! 
—–
The Seattle Times: Arts & Entertainment: Hollywood hopes sequels will reign at box office this summer It seems like every year is the year of sequels. There are only 3 that matters this year though ;)
—–
paperfolding.com is a comprehensive site about origami, including some diagrams, and history and math behind origami. [from /.]
Some more links:
—–
Latest Comments
RSS