Happy Pi Day!

I made a delicious cherry pie this morning, with cherries canned from our trees last summer, and my family pod celebrated by eating the entire thing. I did not manage a picture of it before putting it into my belly, but it looked a lot like last year’s rhubarb pie (aka: Queen Of Pies) at the top of the page, only redder and stickier.

Just dropping onto the blog to wish you all a happy Pi(e) Day today, and to explain the inside math jokes for anyone who is feeling left out in the cold about it. I missed posting on Friday, but what a perfect time for a makeup post, on the most silly mathematical holiday of the year.

You may remember pi from your days in geometry. Pi is a greek letter, π. When we use it in math, it stands for a very specific irrational number:

π = 3.14159… etc

Now, an irrational number, by definition, goes on forever in the decimals without ever establishing a repeating pattern, so I can’t write all of π for you here today, nor can anyone! Nor can I make it into a fraction, because irrational numbers also can’t be made into whole number fractions.

Anyway, we generally consider it good-enough to round pi to the nearest hundredths place:

π ≈ 3.14

Hence, we celebrate Pi Day on March 14th. 3/14 in the American system of dates. (14/3 in the rest of the world, which makes dramatically more sense, but isn’t as much nerdy fun in this case.)

Why the ode to pi?

Well, because pi is the ratio between the circumference of a circle (distance around the circle) and its diameter (distance across the center). Any circle! It’s one of the things that makes a circle a circle and this universe this universe. And I promise you a gif or video about it soon on a day not quite so over as this one already is.

Also:

1. Math people like puns

2. Pi sounds like Pie

3. Pie is delicious

4. Pie is shaped like a circle

So, let’s celebrate by being uber nerds! Here is a cute joke making the rounds of my FB. I’ll explain it below, but give it a try! Remember, math can’t hurt you and there’s no failing this test.

Decoding the joke:

• There’s this famous rule in math that you can’t take the square root of a negative number. And this super tricky-awesome loophole…
  You can’t take the square root of a negative number if you want a REAL answer!
  We get around the rule by inventing a whole system of numbers we dub “imaginary.” They’re not real. Not in the mathematic sense, anyway. The base of this number system is the square root of negative
  We call that special number “i”
  i reads like I

• This is just a power: 2 to the power of 3 means we multiply 2 by itself 3 times so…
  2x2x2 = 8
  8 sounds like ate

• Σ is the capital greek letter sigma. In math, we write this sigma really big to warn everybody that we’re about to add up a whole list of numbers that we write after the Σ
  When we add a list, we are making a sum
  So you might roughly translate this letter as “take the sum of” or, more briefly, “sum…”
  Sum sounds like some

• Lastly, our old friend π, or “pi”
  Which sounds like pie

• I ate some pie, and it was delicious!
  

Got a favorite nerdy joke? Or a favorite kind of pie? Throw it in the comments! I’d love to hear all about it.