by Melanie and Jim
Amaze your friends! Astound your neighbors! Confuse your enemies! Calculate the day of the week for any date, all without consulting a paper OR electronic calendar!
Several years ago my dad, a brilliant man, told me about a calendar trick he used. The trick allowed him to figure the day of the week for nearly any date. While other people were still looking in their paper planners (back in the old days,) he already knew.
Original calendar layout jks Lola – publicdomainpictures.net | Noted dates by Jim and Melanie in IA
In 2014, Friday is the MAGIC DAY, a reference day around which the calendar trick revolves.
Let’s begin with the easy ones:
the 4th day of the 4th month and
the 6th day of the 6th month and
the 8th day of the 8th month and
the 10th day of the 10th month and
the 12th day of the 12th month
ALL fall on the same day of the week, the MAGIC DAY. In 2014 the Magic Day is Friday.
Note that for the EVEN numbered months starting in April, the day and month match up.
Besides those:
the 9th day of the 5th month and
the 5th day of the 9th month and
the 11th day of the 7th month and
the 7th day of the 11th month
ALL fall on the same day of the week, the MAGIC DAY. In 2014 the Magic Day is Friday.
Note how 5 and 9 match up [think “9 to 5”] and 7 and 11 match up [think “7-11”].
That leaves January through March. February and March are simple.
For February, the LAST day of the month is the Magic Day (Friday this year), regardless of whether or not it is leap year.
For March, since the LAST day of February is the Magic Day, the 7th, 14th, 21st, and 28th of March also fall on the Magic Day. Pi Day is the Magic Day!
January is more difficult, but because the last day of February is the reference day, the last day of January is the same day EXCEPT in leap years. In leap year it is the day before the reference day. For example, in 2012, a leap year, the last day of January was Tuesday, not Wednesday. (Go ahead, check the calendar and see.)
Once you know these rules, you can move backward or forward in any month to determine the day of the week. For example, my son’s birthday is on the Magic Day, and mine is two days later. This year his birthday is Friday, so mine must be Sunday.
The reference day progresses through the years. It becomes one day later every year, except in leap years when it advances two days. In 2011, the Magic Day was Monday, and it progressed two days to Wednesday in 2012. In 2013, it was Thursday, and in 2014, it is Friday.
These days when so many people carry smart phones, it may not be as useful as it used to be. But I don’t have a smart phone. I have a dumb phone, and I still use these rules. Do you think you are geeky enough to remember and use these rules?
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Well Melanie, you taught me something new! This is both fascinating and magical 🙂
Awesome, huh? 🙂
My 9-year old son (home sick from school today) is thrilled by this magic! 🙂 So great!! We are practicing…
Hope he feels better soon. In the meantime, enjoy!
Reblogged this on JAR Blog… and commented:
Your mental calendar is ready.
Despite my brain protesting loudly (it usually thinks that by lunch time it’s done enough for one day), I had to put the trick to test. It worked, every time!
Now, if I’m ever without my smartphone…wait…did I say ‘ever without my smartphone’? Ok, no way that’s ever gonna happen…. 😉
🙂
That’s okay. It’s a cool thing to know, anyway.
Whether I actually make use of this information, it is good to know. Makes for great party conversation – like at one of our Fiesta Fridays get-together. I just hope I can remember it well enough to wow others.
It took me quite a while to memorize it, but I have it down now! I still get tripped up on the January rule sometimes, but usually it doesn’t matter. 🙂
Oh Melanie, this is a great icebreaker to bring to Fiesta Friday!! Now, I have to let you know that most of the guests have had way too many Latin Lovers by this point in the party. I’m so glad you wrote this all down for us because some of them will need a little “refresher” in the morning! 😉
Kind of fun and weird, huh? I can make it work easily when I’m fresh. But when I’m worn down it’s all a mystery to me, too. 🙂
what a nice idea you brought some party conversation instead of a cake! so little calories, yet not so easy to digest! But once you thought it through, great to small talk to warm up at a party!
No, not so easy to digest! There was already SO MUCH FOOD. So this was a little different way to celebrate the special day. Thanks for stopping by.
Hubby likes this! Predictable, he is kind of geeky. But I like it, too! Does that make me geeky, then? 🙂
Yes, in your own special way!
I love this! I don’t know if I’m geeky enough to remember all the rules (but it would be fun to try!), but I know just the friend who would memorise the full rules and then show of next time we meet, haha! Thanks for this post, really interesting! 🙂
It certainly is good for those who a) are geeky and b) like to show off their geekiness!
Thanks for taking a look.
Oh my gosh, I’m totally geeking out and printing this page so I can learn the rules. What fun! I am constantly asking myself what date falls on which day so having this memory trick will do wonders, I’m sure. Thank you for sharing this handy chart and all this info!
I haven’t seen this method, but in 1971 I learned a close variant of the method described at
http://en.wikipedia.org/wiki/Determination_of_the_day_of_the_week
in the section entitled “A tabular method to calculate the day of the week.”
On at least one occasion I taught it to a class of high school math students.
I’ll admit, Steve, that this time of day I’m not as functional, so I can’t even read that! It looks a lot more comprehensive and possibly simpler, once learned, than my dad’s method above.
Thanks for taking reading.