Happy Pi Day -- date formats


Happy Pi Day to those of us in the US (and maybe some in Canada).

According to wikipedia the US is mostly alone in its use of MDY date format. So while we can celebrate Pi Day those using DMY date format can celebrate 'e Day' (27/1). A belated Happy e Day to you!

To make this a non-OT topic, I noticed that China, Japan and Korea use YMD format but I've never seen that on an HP calculator. (I'm not sure that I've ever used any non-HP calculator that allowed for date entries in the YMD format.) Considering that almost all calculators are made in this region of the world I find this remarkable. Do calculators that are made to sell in China, Japan and Korea have YMD as date formats?


Edited: 14 Mar 2011, 12:13 p.m.


I haven't seen any that use the YMD format, but I sure would like one. If nothing else, the YMD format makes sorting dates a lot easier.


I spoke too soon. After I changed the batteries in one of my calculators, I noticed it did have a YMD option. It's the 84Plus Silver Edition from that company in Texas. Their 89Titanium also has that option.


I can't answer your question, but have one of my own: For both formats, YMD and DMY, I can come up with a more or less logical explanation. YMD is going from big to small, logically followed by HMS. DMY is presenting the most needed information for every day use first; while you will most certainly remember the year and month you're currently in, the number of the day might escape your attention the easiest and therefor is the most crucial to be noted.

Is there any logic behind MDY? What pupose does this format serve?


Is there any logic behind MDY? What pupose does this format serve?

That matches the way we (at least in the US) talk. If somebody asked me when I was born, I would most likely answer that "I was born on February 17, 1946."

I would usually say "Today is March 14th" although I might also say "Today is the 14th of March."

What does someone in Europe say? "I was born (on?) 17 February, 1946"? Perhaps: from my rusty French recollections, I might well say "Je suis ne le dix-sept fevrier, 1946." (Please excuse any missing accents!)


I think you have it right. I do believe Europeans say the day first, then month, just as we in the U.S. do the opposite.


I think you have it right. I do believe Europeans say the day first, then month, just as we in the U.S. do the opposite.


"Remember, remember the fifth of November [...]" ;-)

It could have changed to "November the fith" and finally, to save time, "November fifth".

In Germany, it is valid grammar to put it the other way round: "Fu"nfter November".


Which reminds me of this little gem:

Q: Who is the only man to enter Parliament with good intentions?

A: Guy Fawkes

True then and still true now :-(

- Pauli


And on the periphery of calculator display discussions, who chose the bizarre format of the HP 49/50 TIME and DATE display at the top of LCD?

An example of 49/50 format is: "17:21 MAR:14"

There's no SECOND or YEAR information, the MONTH is non-numeric, and a very non-standard ":" is used to separate month from day.

The earlier format used on the 48 series is much better: "03/14/11 17:21:42"

Even if there is not enough space for the 49/50 LCD to accomodate all the information in the 48 series format, even "03/14 17:21" would be far better than what the 49/50 series uses.

I kept hoping over the years the one of the 49/50 firmware updates would correct the error of using an ALPHA month label and a colon as month-day delineator.


I am running Meta Kernel on my HP-48GX, and it is interesting to see that it also uses the less desirable 49/50 style of date and time display. I suppose that there is a certain consistency there.


YMD format is actually ISO standard (http://en.wikipedia.org/wiki/ISO_8601) and is used all across the world (especially with IT, military and government). It is also national standard in many countries, including many European. Due to spread of computers, it is becoming more and more popular.


No more Pi days, then. Anywhere.


If you allow 9 instead of 09, then Sept 26 in the year 31415 qualifies!


Well, things are not so bad for us geeks. Computers mainly speak binary, so "Binary Pi days" happen!

When is the nearest one?


It becomes 03-14 instead of 03/14, in ISO 8601. Still same MD order, just Y moves in front.

Any other format is middle-endian, which makes no sense, IMO. (Even the European DMY standard - because with two digit day and month, and a four digit year, here are the numbers in order of significance:


That is, it's most important that you get the millenium right, so on, so on.

In DMY, you get something like this:



At least it's not as middle-endian as MDY:


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