On non-leap-years, the date/day relationship in February is identical to the date/day relationship in March, excepting the last three days, obviously. The first Monday in February this year is the 7th, and so is the first Monday in March.
Useful!
–Howard
I just figured out that you can do the same trick with the other months if you add three days for months with 31 and two for months with 30.
Today being Wednesday, January 19, without looking at a calendar, we get:
February 19 = Saturday
March 19 = Saturday
April 19 = Tuesday
May 19 = Thursday
June 19 = Sunday
July 19 = Tuesday
August 19 = Friday
September 19 = Monday
October 19 = Wednesday
November 19 = Saturday
December 19 = Monday
This is a handy trick I will try to remember!
Or, for a general rule: (Number of days in month 1) – 28, added to the day of the date in month 1, gives you the day of the date in month 2.
pish number of days % 7 🙂
Now if I remembered the number of days in each month…
Some things just never stick, and I don’t know why.
I suppose it’s like that left/right dichotomy that some folks can’t pick up.
30 days hath September / April, June and November…
+–Dragonbane–
I’ve heard that. It hasn’t stuck before. But the last time I tried was at least a decade ago, so who knows? Thanks.
I also never considered just remembering _that_ part of it, making the rest implicit (and everybody knows about february, right?)
:repeats mantra:
four things is a much happier chunk than twelve.
That’s the only part of that I’ve got memorized also.
“All the rest have thirty-one, except February alone.” You don’t have to memorize the other months individually, eh?
You can use the counting on your hand method.
Start on the knuckle of your pointer finger, that’s January. Then the dip between knuckles is February. Like this:
Pointer Knuckle -January
dip – February
Middle knuckle -March
dip -April
Ring knuckle -May
dip – June
Pinky knuckle -July
Now you’ve run out of knuckles, so start on the pinky knuckle and move backwards.
Pinky knuckle -August
dip -September
Ring Knuckle -October
dip -November
Middle knuckle – December.
All the months that land on knuckles have 31 days. All the months that land on dips have 30 days except for February which everyone knows is weird anyway.
I really should read entire threads before commenting. I wouldn’t have needed to type all of that.
But if you delete this post, no one need know you came second! Your post shows up first because you replied to an earlier comment.
Eee! You start at the pointer?
I always start with the pinky knuckle of my left hand… then my pointers are July and August. (August is on my right hand.)
“Now you’ve run out of knuckles, so start on the pinky knuckle and move backwards.”
I actually do it that way myself, but in the reply I posted below I opted for the “start over” approach instead because it’s easier than trying to remember whether you count the pinky once or twice.
The “other hand” approach works too, but it’s a little more obvious what you’re doing in that case, so other people get the opportunity to point and snicker at the idiot who can’t memorize “Thirty days hath September, August, May, and December.”
Of course, in reality, I’m never more than a couple of feet from my Palm, so I let it handle the calendar calculations.
Now I’m really confused.
Do I use my *knuckles* or my PALM??
The mnemonic I’ve always used is one I know just like the back of my hand, because it is the back of my hand.
Clench your fist. Begin counting at the knuckle of your index finger. That knuckle will be January. The space between it and the knuckle of your ring finger will be February. The knuckle of your ring finger will be March, and so on. You should reach the knuckle on your pinky at July, at which point the non-polydactyls among us will run out of knuckles (or “piddies,” for the Tweety fans.) At that point, just start over with the knuckle of your index finger at August. (If you are a polydactyl, you are now screwed up comparably to those of us lefthanders who were taught the mnemonic that “your RIGHT hand is the one you WRITE with.”)
Months that end up on knuckles have 31 days. Months that end up in valleys, other than February, have 30 days. You’ll have to figure February out for yourself.
Another useful date-calculation trick is to treat days in the next month as days in an extension of this month. So Valentine’s Day, for example, is the 14th of February which is also the 45th of January. That makes it 26 days away from today, so it’s on a Monday (26 is 2 less than 28, which is a multiple of 7.) Obviously this trick is a bit less useful if the date you’re interested in is more than a month off, but if you’re trying to figure out the date of the first payday next month it can come in handy.
I guess it would be, since 28 is a multiple of 7.
Wait, did I just actually reference the multiplication tables? That’d been a while.
Yeah, that’s why I’m chiding myself for not having figured it out sooner. I can do maths. The Schlock Buffer is an ongoing exercise in multiples of seven.
Up until now, though, the only date thingy I could remember is that Christmas is the weekday before Hallowe’en: INCREDIBLY useful, since those are my two bestest holidays ever. 🙂
Christmas is exactly one week before New Year’s Day. Unless they change December to give it 32 days or something.
If you’re interested in doing day-of-week calculations in your head, check out the Doomsday Algorithm
That reminds me, you haven’t mentioned the buffer lately. How’s it doing?
Buffer tracking can be found here (2nd thread from the top). Right now it’s at 17. I’ve been having a hard time getting ahead, what with the commercial project I’ve contracted for December, January, and March, but I haven’t fallen BEHIND, either.
–Howard
I’ve known it for years. I happened to notice that if February had a Friday the 13th, March would too, on non-leap years.
Pure luck. But — was it good luck, or bad luck?
🙂
Another useful fact: The calendar repeats every 28 years, at least from 1900 through 2099. I run non-Y2K-compliant mainframe software with a date 28 years in the past so the days come out the same.
You and I have differing definitions of “useful.” I mean, obviously it’s useful for your mainframes, but unless I keep 28 years of calendars around for recycling, that’s not going to do me a lick of good. 🙂
(okay, maybe if I’m accessing services on these manlyframes of yours, but how would I even know?)
–Howard
How in the world do you have a mainframe, much less software to run on it??
Bro, this is Jay Maynard the Tron-guy you’re talking to. The mainframe is like a second bedroom for him. 😉
–Howard
Now that you mention it… duh. 🙂