Random knowledge record #1

I had a few things written down in different places, strewn on the post-its and scraps. Now they shall be consolidated, promulgated, and Google-indexed.

1. Some say that one can determine the temperature in ºF by counting the number of times a nearby cricket chirps in 15 seconds and adding 40.

2. "Pogue mahone" means something like "kiss my ass" to folks more Irish than me.

3. One can determine the day of the week on which any date will fall, with MATH! Through a series of painful but useful calculations, below, I shall attempt to elucidate the secrets of John Conway's Doomsday rule.

Starting with the more practical elements of the Doomsday rule:
• this year, 2008, the Doomsday is Friday.
• Doomsdays fall on the following dates: 1/10 or 1/11 (depending on the leapitude of the year), 3/0 (meaning the day before 3/1), 4/4, 5/9, 6/6, 7/11, 8/8, 9/5, 10/10, 11/7, & 12/12
• These dates are the easiest for me to remember because of their numerical symmetries.
• e.g., If asked, "June 23rd, what day will that be?" You may now quickly realize that June 6th is a Friday, and so is every 7 days after that. So the 23rd must be a Monday (3 days after Friday, June 20).

What happens next year? What about distant dates? What about the day you were born? Clearly that was a Dooming Day, but was it a doomsday? Enter math, stage left.

First, you'll need a "century anchor day". This century that day is Tuesday. Odds are, it will be the only anchor day you'll ever need. So, Tuesday, remember that, or die.

Second, you'll need a lovely little modulo equation. (N.B. For our purposes, a modulo is an operator that takes a dividend and a divisor and gives back the remainder. If the dividend is less than the divisor, it gives back the dividend. So, 20 modulo 7 = 6. 54 mod 4 = 2. 3 mod 7 = 3. 5 mod 2 = 1. Got it?)

The system of equations:

Doomsday in a certain year = {[d + (d/4)] mod 7} days after Tuesday
where d = the last two digits of that year.

Por ejemplo, M.I.A.'s birthday in 2012 (Mayan Armageddon Year Anyone?) will be on a Friday.

2012 ==> d = 12
(12 + 12/4) mod 7 = 15 mod 7 = 1
1 days after Tuesday is Wednesday, which is the Doomsday in 2012.
July 17 is Mathangi Arulpragasam's birthdate.
July 11 (7/11) is a Doomsday.
Her birthday is 6 days after a Doomsday (Wednesday in 2012), so it's on a Tuesday.
Check it July 17, 2012 is a Tuesday.

Just to make sure we've got it, what day does Johnny Appleseed Day (September 26) fall on in 2048?

I got Saturday, I hope that's right. For more in depth explanation of why this works...