People of the media: "pi" is a mathematical concept. As such, those pesky digits actually mean something. Dates actually mean something, too, but that's a completely different concept. Also, "pi" and "pie" share common letters and pronunciation, but have little else in common (other than the fact that many pies are, in one dimension, circular). So "Pi Day" already combines three unrelated things, and is really just a fun thing to do. I support this. It's a great opportunity to focus the public's attention on a math! But, let's take the opportunity to represent the math correctly. Get the word out that the real high-precision Pi Day is next year: 3/14/16.
It is really irritating me that we are so casually saying that this year is a super special one for Pi Day. Why? Because tomorrow is "3/14/15," and pi, to 6 significant digits, is 3.14159. I threw that '9' in there because pi, to 5 significant digits is 3.1416. We have this concept of "rounding" for a good reason. Especially with irrational numbers, there is no way to precisely capture the actual number with digits. With every additional digit, the representation is a bit closer to the actual number, but it never gets there completely. (This is one reason we represent the ratio of a perfect circle's circumference to its diameter with a name -- "pi" -- rather than a digital representation.) Although you can never use digits to perfectly capture pi, you can capture something close, with measurable accuracy. For example, I could say that pi, to 5 significant digits, is 3.4567. That would be much less accurate than using the number 3.1415. It would be more accurate to say that it is 3.1416. This is true for the same reason that the number 59 is closer to the number 60 than it is to 50, or that someone who is 5'11" tall is more likely to say that they are "6 feet tall" rather than "5 feet tall."
So, sure, "Pi Day" is a fun gimmick, but it's one that draws public attention to mathematics in a way that few other other fun things do. Why use the event to spread mathematical ignorance? I'm looking at you, +HuffPost Live