How to figure out the day of the week by the date - Tilted Forum Project - TFP - Sexuality, Philosophy and Political Discussion

twistedmosaic · 01-03-2008, 01:12 PM

Ignore the goofy url, this is a really fascinating mental exercise. I just started reading it, but i'm definitely going to try to commit it to memory:

http://www.h2limousine.com/calendar2.php

Basically, the day of the week (1=sunday, 2= Monday...0=saturday) is:

(Month code + year code + day of the month) mod 7.

Month codes:
January: 1
February: 4
March: 4
April: 0
May: 2
June: 5
July: 0
August: 3
September: 6
October: 1
November: 4
December: 6

Year codes:
2005: 5
2006: 6
2007: 0
2008: 2
2009: 3
2010: 4

The 'mod' operation means 'subtract seven until you can't subtract seven any more without getting a negative number. Thus, Mod 25 would be [ 25-7 (18) - 7 (11) - 7 ] =4

A practical example. My sister's birthday is April 15th. Her 21st is this year, and I'm curious whether it's on a weekend, as she wants me to come out.
Month: 0
Year: 2
Day: 15

17 mod 7 = 3. d'oh, it's a Tuesday.

That's the cliff notes version, but check out the site if it at all interests you

Anyone else have any cool math tricks? I class this about three times as easy as memorizing a substancial number of digits of pi (which I still have out to 3.141592653589793238...used to have more), and thirty times as useful

troit · 01-03-2008, 01:57 PM

Pretty cool....

Bill O'Rights · 01-03-2008, 02:57 PM

Wouldn't it be easier to just look at a calender?
Mine says that you are correct. Your sister's birthday is on a Tuesday.

twistedmosaic · 01-03-2008, 03:24 PM

Quote:

Originally Posted by Bill O'Rights

Wouldn't it be easier to just look at a calender?
Mine says that you are correct. Your sister's birthday is on a Tuesday.

Once you memorize the month codes, and, at most, this year and the next, you can do this on the fly, in your head, anywhere, extremely fast.

So, probably yes, if you have a calendar in front of you, and it's already open to the right month. If you have to flip for the month, probably not. If you don't have a calendar, definitely not.

dlish · 01-05-2008, 01:51 PM

you double click on the clock setting in the right hand corner of your desktop and u can find out like that! no need for finger calculations

pig · 01-05-2008, 01:59 PM

Maybe a useful mental exercise...I tend to use my Palm for this type of thing...which may or may not be sad, depending on who you ask.

Crompsin · 01-05-2008, 02:03 PM

Great party trick.

Byrnison · 01-05-2008, 02:20 PM

That appeals to my inner geek

Unfortunately, I suffer from CRS and would probably never be able to commit those month/year values to memory

As an aside, the mod function is the remainder of the formula if you apply long division to it. In your examples:
7 into 25: 3 remainder 4 (3 x 7=21, 25-21=4)
7 into 17: 2 remainder 3 (2 x 7=14, 17-14=3)

If you grew up learning long division, it might be a wee bit easier to do it in your head that way as opposed to trying to do the subtraction steps.

/geek

twistedmosaic · 01-06-2008, 12:34 AM

I've decided to commit this process to memory. This involves three steps.

1. Associate pictures with each number, 0 through 9 (I went ahead and did 0 through 10)
2. Associate pictures with each month
3. Assemble these pictures into twelve scenes, one for each month, involving each month and code's number.

So far, I've memorized images for each number. It was super easy. Byrnison, try it! It only took me a lunch today do, and I'm slightly drunk and still remember them all. I just made these up, feel free to use your own list. I saw some lists online that looked pretty lame...remember, you're going to have to put these objects in scenes to remember other stuff...having a 'baseball team' for number 9 just seems unwieldy and not very flexible. (eg, I'd rather imagine a cat in a bucket for 95 than a baseball team in a bucket). There are a lot of tricks you can do with this list once you have it down, not just this one. I'll probably start a new 'memory tricks' thread once I get more time to research them.

Here's mine:

1. The one ring from lord of the rings
2. Two penguins (who mate for life)
3. A tree--sounds like three, and 'three on the tree' from old motorsports resonates
4. Door. Sounds like four, my picture has four panels, and i'm on the market for a '4-door' aka sedan
5. Bucket...a five gallon bucket
6. Gun. specifically a Six Shooter
7. Dice. Seven is the most common dice roll, also 'seven come eleven!'
8. Ball. Magic 8 ball says, this will be easy to remember
9. Cat. Cat o' nine tails or cats with nine lives, depending on whether i'm in a kinky mood or not
10. Tin can. Ten sounds like tin, plus my image is a tin can radio, with one can standing up and one laying down that looks like a ten
Zero. An egg. I knew someone who used "The ol' goose egg" as slang for zero or nothing, plus they're both round.

Once you pick out your ten (or eleven) images, find clipart that makes you happy for each one, and print that sheet. Study it a few times, then flip it over and try to draw all 11 pictures from memory. Then do it again. And again. Three times was enough for me to have them pretty permanently etched.

Tomorrows task: Month pictures (and more drilling on the number pictures to make sure they stuck).

allaboutmusic · 01-06-2008, 04:31 AM

Going to try this. I've always been fascinated with those savants who can do calendar calculations - I wonder if their internal method is based on this at all?

twistedmosaic · 01-06-2008, 02:00 PM

Quote:

Originally Posted by allaboutmusic

Going to try this. I've always been fascinated with those savants who can do calendar calculations - I wonder if their internal method is based on this at all?

I'd say devote a day to each stage of the image memorization. I still have my number pictures

Now workng on my set of month pictures.

twistedmosaic · 01-07-2008, 01:14 PM

OK, got my month pictures:

January: Cell phone (CES is in January every year)
February: Heart
March: Drum major's hat
April: Stack of coins
May: Flowers
June: Squirt gun
July: Uncle Sam's Hat
August: Cake (my birthday!)
September: Backpack (full of school books)
October: Jack o'lantern
November: Turkey
December: Present

My month codes that I need to memorize, therefore, are:

Cell phone + Ring
Heart + Door
Drum Major Hat + Door
Stack of coins + Egg
Flower + Penguins
Squirt Gun + Bucket
Uncle Sam + Egg
Cake + Tree
Backpack + Revolver
Pumpkin + Ring
Turkey + Door
Present + Revolver

The year codes are in order the next three years, so at least for then, I can 'cheat' the memorization of those.

01-03-2008, 01:12 PM	#1 (permalink)
twistedmosaic Inane Join Date: Jan 2004 Location: Wunderland	How to figure out the day of the week by the date Ignore the goofy url, this is a really fascinating mental exercise. I just started reading it, but i'm definitely going to try to commit it to memory: http://www.h2limousine.com/calendar2.php Basically, the day of the week (1=sunday, 2= Monday...0=saturday) is: (Month code + year code + day of the month) mod 7. Month codes: January: 1 February: 4 March: 4 April: 0 May: 2 June: 5 July: 0 August: 3 September: 6 October: 1 November: 4 December: 6 Year codes: 2005: 5 2006: 6 2007: 0 2008: 2 2009: 3 2010: 4 The 'mod' operation means 'subtract seven until you can't subtract seven any more without getting a negative number. Thus, Mod 25 would be [ 25-7 (18) - 7 (11) - 7 ] =4 A practical example. My sister's birthday is April 15th. Her 21st is this year, and I'm curious whether it's on a weekend, as she wants me to come out. Month: 0 Year: 2 Day: 15 17 mod 7 = 3. d'oh, it's a Tuesday. That's the cliff notes version, but check out the site if it at all interests you Anyone else have any cool math tricks? I class this about three times as easy as memorizing a substancial number of digits of pi (which I still have out to 3.141592653589793238...used to have more), and thirty times as useful __________________ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ Last edited by twistedmosaic; 01-03-2008 at 01:16 PM.

01-03-2008, 01:57 PM	#2 (permalink)
troit Transfer Agent Super Moderator Join Date: Apr 2003 Location: NYC	Pretty cool.... __________________ I've yet to dephile myself...

01-03-2008, 02:57 PM	#3 (permalink)
Bill O'Rights will always be an Alyson Hanniganite Super Moderator Join Date: May 2003 Location: In the dust of the archives	Wouldn't it be easier to just look at a calender? Mine says that you are correct. Your sister's birthday is on a Tuesday. __________________ "I distrust those people who know so well what God wants them to do because I notice it always coincides with their own desires." - Susan B. Anthony "Hedonism with rules isn't hedonism at all, it's the Republican party." - JumpinJesus It is indisputable that true beauty lies within...but a nice rack sure doesn't hurt.

01-05-2008, 01:51 PM	#5 (permalink)
dlish Currently sour but formerly Dlishs Moderator Join Date: Oct 2004 Location: Australia/UAE	you double click on the clock setting in the right hand corner of your desktop and u can find out like that! no need for finger calculations __________________ An injustice anywhere, is an injustice everywhere "Romance is never having to apologize for getting it in her hair" - World's King

01-05-2008, 01:59 PM	#6 (permalink)
pig pigglet pigglet Join Date: Apr 2004 Location: Locash	Maybe a useful mental exercise...I tend to use my Palm for this type of thing...which may or may not be sad, depending on who you ask. __________________ You don't love me, you just love my piggy style

01-05-2008, 02:03 PM	#7 (permalink)
Crompsin STRIKE FACE Join Date: Jun 2007 Location: Prime Self	Great party trick. __________________ C19H28O2 = C6H2(NO2)3CH3 Merleniau: "Your face is old and moldy!"

01-05-2008, 02:20 PM	#8 (permalink)
Byrnison Tilted Join Date: Sep 2007 Location: Los Angeles, CA	That appeals to my inner geek Unfortunately, I suffer from CRS and would probably never be able to commit those month/year values to memory As an aside, the mod function is the remainder of the formula if you apply long division to it. In your examples: 7 into 25: 3 remainder 4 (3 x 7=21, 25-21=4) 7 into 17: 2 remainder 3 (2 x 7=14, 17-14=3) If you grew up learning long division, it might be a wee bit easier to do it in your head that way as opposed to trying to do the subtraction steps. /geek __________________ Knowledge is raw data. Wisdom is knowing how to use it. ~ Solomon Short

01-06-2008, 12:34 AM	#9 (permalink)
twistedmosaic Inane Join Date: Jan 2004 Location: Wunderland	I've decided to commit this process to memory. This involves three steps. 1. Associate pictures with each number, 0 through 9 (I went ahead and did 0 through 10) 2. Associate pictures with each month 3. Assemble these pictures into twelve scenes, one for each month, involving each month and code's number. So far, I've memorized images for each number. It was super easy. Byrnison, try it! It only took me a lunch today do, and I'm slightly drunk and still remember them all. I just made these up, feel free to use your own list. I saw some lists online that looked pretty lame...remember, you're going to have to put these objects in scenes to remember other stuff...having a 'baseball team' for number 9 just seems unwieldy and not very flexible. (eg, I'd rather imagine a cat in a bucket for 95 than a baseball team in a bucket). There are a lot of tricks you can do with this list once you have it down, not just this one. I'll probably start a new 'memory tricks' thread once I get more time to research them. Here's mine: 1. The one ring from lord of the rings 2. Two penguins (who mate for life) 3. A tree--sounds like three, and 'three on the tree' from old motorsports resonates 4. Door. Sounds like four, my picture has four panels, and i'm on the market for a '4-door' aka sedan 5. Bucket...a five gallon bucket 6. Gun. specifically a Six Shooter 7. Dice. Seven is the most common dice roll, also 'seven come eleven!' 8. Ball. Magic 8 ball says, this will be easy to remember 9. Cat. Cat o' nine tails or cats with nine lives, depending on whether i'm in a kinky mood or not 10. Tin can. Ten sounds like tin, plus my image is a tin can radio, with one can standing up and one laying down that looks like a ten Zero. An egg. I knew someone who used "The ol' goose egg" as slang for zero or nothing, plus they're both round. Once you pick out your ten (or eleven) images, find clipart that makes you happy for each one, and print that sheet. Study it a few times, then flip it over and try to draw all 11 pictures from memory. Then do it again. And again. Three times was enough for me to have them pretty permanently etched. Tomorrows task: Month pictures (and more drilling on the number pictures to make sure they stuck). __________________ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻

01-06-2008, 04:31 AM	#10 (permalink)
allaboutmusic Aurally Fixated Join Date: Oct 2007	Going to try this. I've always been fascinated with those savants who can do calendar calculations - I wonder if their internal method is based on this at all?

01-07-2008, 01:14 PM	#12 (permalink)
twistedmosaic Inane Join Date: Jan 2004 Location: Wunderland	OK, got my month pictures: January: Cell phone (CES is in January every year) February: Heart March: Drum major's hat April: Stack of coins May: Flowers June: Squirt gun July: Uncle Sam's Hat August: Cake (my birthday!) September: Backpack (full of school books) October: Jack o'lantern November: Turkey December: Present My month codes that I need to memorize, therefore, are: Cell phone + Ring Heart + Door Drum Major Hat + Door Stack of coins + Egg Flower + Penguins Squirt Gun + Bucket Uncle Sam + Egg Cake + Tree Backpack + Revolver Pumpkin + Ring Turkey + Door Present + Revolver The year codes are in order the next three years, so at least for then, I can 'cheat' the memorization of those. __________________ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ ☻☻☻☻☻☻☻☻☻☻ Last edited by twistedmosaic; 01-07-2008 at 01:17 PM. Reason: Automerged Doublepost