Dear reader, it's the fourteenth day of the third month of the year, and if you're reading this blog, some charlatans or overenthusiastic youth (the subject of whose enthusiasm is not what they think it is) have probably tried to convince you to celebrate it as "Pi Day." You see (these quacks implored you) π is around 3.14, and March fourteenth is 3/14. And *furthermore* (they may have put to you) furthermore *this* year's Pi Day is special, because it's 3/14/15, which is like 3.1415! Why (an especially impudent few might have continued to venture), we should plan some grand spectacle on 9:26 a.m. on the day, which is like 3.1415926! With (and this is the part that is most inevitable and offensive) pie! Get it, because it sounds like *pi* and is shaped like a circle?

Dear reader, it is lies or it is worse than lies; it is blasphemy, treason, superstitious superficiality, degenerate folderol, and frivolous depravity! Do not mistake me; of course I can see as clearly as any other ape can that the *numeric subsequence* of the *string* "3.14" is same as that of the *string* "3/14". The former string represents an occasionally useful approximation of the circle constant which is ubiquitous in mathematics (give or take a factor of two); the latter is how people in my country abbreviate today's date. Perhaps to those who don't have anything really interesting to think about, this trivial coincidence might be worth a passing mention; apes love anything for an innocent distraction, and why begrudge that?

What is intolerable, however, is for a *mathematically meaningless* coincidence to be *marketed* as a day to celebrate mathematics, which marketing can only propagate the cruel slander that mathematics is about memorizing and manipulating figures. Not that seekers of true mathematical knowledge don't have occasion to manipulate figures from time to time—we do—but we do it because the figures *actually mean something*. And the similarity between the decimal number "3.14" and the date "3/14" ... *doesn't* really mean anything. Our dominant culture happens to prefer a base-ten place-value system, in which the representation of the quantity π happens to start with 3.14. That *means*: three (times ten-to-the-zeroth), plus one-tenth (which is one times ten-to-the-negative-first), plus four one-hundredths (which is four times ten-to-the-negative-second), plus other terms that our to-two-decimal-places approximation neglects. Whereas 3/14 *means*: the fourteenth day of the third month. It's not the same number as 3.14, even if its standard representation happens to involve the same digits in the same order.

If there must be a Pi Day, I can imagine sensible arguments for holding it once every three years and fifty-two days (around π years), or on January fourth at 3:23 *a.m.* (about π days into the new year), or on one of the solstices or equinoxes (when the Earth is π radians around the sun from some imagined "zero" at the opposite solstice or equinox).

But *March fourteenth*? What is *wrong* with the world such that such a travesty could gain common currency? Can't our innocent distractions at least rise to making a *pretense* of meaning something? Don't our cultural symbols deserve to have *semantics* deeper than mere empty tokens that can only be recognized, compared, and gawked at?

For the children.

I wouldn't object that much to an annual event. A year has approximately π*10^7 seconds, after all, and the second is the only SI unit for time. But yeah, 3/14 doesn't make any more sense than any other date, especially since it relies on the way Americans write them...

Preach it.

Insofar as any simple numerical date can be said to represent the successes of mathematics, I fear the best we can do is celebrate the leap day, February 29th when it occurs, as an acknowledgement that the Platonic dream is dead and the Year is not divisible by the Day.

3 years and 52 days doesn't fit. Pi counts things within a rotation; it doesn't count rotations. January 4th also doesn't work, since pi doesn't have anything to do with the relationship between days and years. I think it has to be February 28, when we are one radian into the year. Luckily, it's the same date on leap years, just at a different time.

The real reason pi day doesn't exist is because April only has 30 days.

@Paul Jarc:

One radian into the year has nothing to do with which circle constant is used. It could just as easily celebrate Tau (see tauday.com), which may be a "better" circle constant. Even so, "Radian Day" on February 28th would be more meaningful than "Pi Day" in its current form.

As for astronomically-based Pi Day celebrations, there are already solstice traditions dating to antiquity. I think perihelion and aphelion (about two weeks after the December and June solstices, respectively) would be more appropriate.