# March 14th - Happy Pi Day everyone!! **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [March 14, 2011, 5:03am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624 "2011-03-14T05:03:38Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![thirdwarning](https://avatars.discourse-cdn.com/v4/letter/t/ecccb3/32.png) [@thirdwarning](https://boards.straightdope.com/u/thirdwarning)\ **Post date:** [March 15, 2011, 6:04pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/21 "2011-03-15T18:04:30Z")
> [@Hari\_Seldon](#): > > Not only that, it is my wedding anniversary! First thing I said to my wife of 47 years this morning was “Happy Einstein’s birthday!” It’s my wedding anniversary, too. Only thirty here, though. So, belatedly, happy pi day, happy Einstein’s birthday, and happy anniversary to you and your lovely wife. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [March 16, 2011, 4:17am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/22 "2011-03-16T04:17:52Z")
_Circle, I’ve got your number digits so sweet and fine circumf’rence over diameter three point one four one five niiiine three point one four one five niiiine_ I think you can guess the tune. 🙂 ---
**Author:** ![flatlined](https://avatars.discourse-cdn.com/v4/letter/f/eb9ed0/32.png) [@flatlined](https://boards.straightdope.com/u/flatlined)\ **Post date:** [March 16, 2011, 4:53am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/23 "2011-03-16T04:53:53Z")
**RTFirefly** I’m not sure if I want to have your babies for that, or kill you for the mindworm. Well done 🙂 ---
**Author:** ![alindallas](https://avatars.discourse-cdn.com/v4/letter/a/f17d59/32.png) [@alindallas](https://boards.straightdope.com/u/alindallas)\ **Post date:** [March 17, 2011, 11:10am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/24 "2011-03-17T11:10:54Z")
Damn you, Firefly! Now I’m off to YouTube to listen to “Jenny”! ---
**Author:** ![dhkendall](https://avatars.discourse-cdn.com/v4/letter/d/a9adbd/32.png) [@dhkendall](https://boards.straightdope.com/u/dhkendall)\ **Post date:** [March 17, 2011, 5:32pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/25 "2011-03-17T17:32:20Z")
My Facebook status on March 14 (and still is, as I rarely change it) was: > [@](#): > > Yes, I like a happy, beautiful pi holiday. I’ll leave it without comment, as I know Dopers are smart enough to see what I just did there. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [March 18, 2011, 1:39pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/26 "2011-03-18T13:39:57Z")
> [@flatlined](#): > > Big sighs here. I’m a geek. Its well known that I’m a geek. I laugh myself silly over shaggy dog jokes, I work 42 into casual conversation, when I’m on hold I’ll often hand calculate Pi and will show how far I got as examples of long hold times “Look! 6 pages! SIX!!! I hate calling this company.” I also NEVER cook food to share at work. > > For the 3rd 3.14 in a row, I baked a pie and took it to work. I’ll even say “Happy Pi Day” while offering it to my coworkers. > > Nobody has ever gotten it ☹ Please, do tell how do you hand calculate pi? Is it by an infinite series of fractions? ---
**Author:** ![brewha](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@brewha](https://boards.straightdope.com/u/brewha)\ **Post date:** [March 18, 2011, 1:52pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/27 "2011-03-18T13:52:17Z")
My daughter is a pi baby. I was actually a little dissapointed when 1:59 AM passed, since I knew she wouldn’t make it to 1:59PM. And 3.14.5:34 doesn’t mean a whole lot. Yes, she did get pie instead of cake for when she turned two last week! ---
**Author:** ![Electric\_Warrior](https://avatars.discourse-cdn.com/v4/letter/e/ee7513/32.png) [@Electric\_Warrior](https://boards.straightdope.com/u/Electric_Warrior)\ **Post date:** [March 18, 2011, 5:29pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/28 "2011-03-18T17:29:24Z")
Some friends had their daughter at exactly 1:59 AM on Monday morning. Now they’re worried she might grow up to be a mathematician. 😉 ---
**Author:** ![flatlined](https://avatars.discourse-cdn.com/v4/letter/f/eb9ed0/32.png) [@flatlined](https://boards.straightdope.com/u/flatlined)\ **Post date:** [March 19, 2011, 3:38am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/29 "2011-03-19T03:38:09Z")
> [@AaronX](#): > > Please, do tell how do you hand calculate pi? Is it by an infinite series of fractions? HURRAY!!! A geek question for me 😃 Pi= circumference / diameter. It doesn’t matter how large the circle is, the math works out the same always. I’ve never used fractions for Pi, its always been long division. Plug in the numbers and start subtracting. I’m kinda new…was this my first woosh? If not, I’d be thrilled to talk Pi with you…cause I don’t understand how one would use fractions for Pi. ---
**Author:** ![flatlined](https://avatars.discourse-cdn.com/v4/letter/f/eb9ed0/32.png) [@flatlined](https://boards.straightdope.com/u/flatlined)\ **Post date:** [March 19, 2011, 3:40am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/30 "2011-03-19T03:40:15Z")
> [@Electric\_Warrior](#): > > Some friends had their daughter at exactly 1:59 AM on Monday morning. Now they’re worried she might grow up to be a mathematician. 😉 I’m afraid that it might be even worse than that. She might grow up to be an engineer :eek: ---
**Author:** ![surrounded\_by\_literalists](https://avatars.discourse-cdn.com/v4/letter/s/8baadc/32.png) [@surrounded\_by\_literalists](https://boards.straightdope.com/u/surrounded_by_literalists)\ **Post date:** [March 19, 2011, 4:40am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/31 "2011-03-19T04:40:20Z")
Next year, you are invited to the Community College where I work. A week before pi day we set up a jar for each science professor. Students, staff and faculty put money in the jar of the professor that they wanted to see get a pie in the face. Some shenanigans similar to episodes of ‘Survivor’ transpired (long story), but in the end, our psychology professor was pi-ed. Good times! ---
**Author:** ![Autolycus](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@Autolycus](https://boards.straightdope.com/u/Autolycus)\ **Post date:** [March 19, 2011, 5:43am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/32 "2011-03-19T05:43:37Z")
Well, Pi Day has come and gone. It was fun while it lasted, but now it is time to look forward to… Tau Day! While it does not have the same cool, hipster aura to it, it is clearly a superior day. In fact, one could even say it is perfect. To Tau Day! > **[No, really, pi is wrong: The Tau Manifesto](https://tauday.com/)** > > For millennia, the circle has been considered the most perfect of shapes, and the circle constant π captured the geometry of the circle in a single number. But π is wrong, and it’s time to set things right. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [March 19, 2011, 6:19am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/33 "2011-03-19T06:19:39Z")
> [@flatlined](#): > > HURRAY!!! A geek question for me 😃 > > Pi= circumference / diameter. It doesn’t matter how large the circle is, the math works out the same always. > > I’ve never used fractions for Pi, its always been long division. Plug in the numbers and start subtracting. > > I’m kinda new…was this my first woosh? If not, I’d be thrilled to talk Pi with you…cause I don’t understand how one would use fractions for Pi. I know, but you need accurate values for circumference and diameter. Do you just draw a large circle and measure them? I did a maths class that mentioned a few ways to calculate pi. Looking at the Wikipedia page, there are several infinite series for pi, which you could use to calculate it by hand. The difficult part is when you get to smaller and smaller decimal places, which is why I was wondering how you could calculate it to 6 pages. Oh, there are more formulae at [Pi Formulas -- from Wolfram MathWorld](http://mathworld.wolfram.com/PiFormulas.html) ---
**Author:** ![flatlined](https://avatars.discourse-cdn.com/v4/letter/f/eb9ed0/32.png) [@flatlined](https://boards.straightdope.com/u/flatlined)\ **Post date:** [March 19, 2011, 7:34am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/34 "2011-03-19T07:34:49Z")
> [@AaronX](#): > > I know, but you need accurate values for circumference and diameter. Do you just draw a large circle and measure them? > > (snip) As a geek, all of my math stuff involves measureing Dinty Moore Stew cans. I couldn’t draw a good circle to save my life. But, honestly…it doesn’t matter how big the circle is, the math will work out. > > I did a maths class that mentioned a few ways to calculate pi. Looking at the Wikipedia page, there are several infinite series for pi, which you could use to calculate it by hand. The difficult part is when you get to smaller and smaller decimal places, which is why I was wondering how you could calculate it to 6 pages. > > (more snips) > > the best thing about Pi is that its anyone can do the paper and pencil by hand. Lots of people done’t understand that long division is just subtraction compounded so they are frightened to try. > > Oh, there are more formulae at [Pi Formulas -- from Wolfram MathWorld](http://mathworld.wolfram.com/PiFormulas.html) I think that we need to keep this thread open…because you are trying to learn how irrational us geeks can be. PS.. Pi is an irrational number ---
**Author:** ![NomadUK](https://avatars.discourse-cdn.com/v4/letter/n/a88e57/32.png) [@NomadUK](https://boards.straightdope.com/u/NomadUK)\ **Post date:** [March 19, 2011, 10:27am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/35 "2011-03-19T10:27:52Z")
> [@Autolycus](#): > > Well, Pi Day has come and gone. Well, as someone noted earlier, for those of us whose dates aren’t backward, Pi Day should actually be 31 April – which maps conveniently to 1 May, which is May Day, so a twofer! Which makes Tau Day 62 August, or 1 October. Easily remembered! Or maybe they should just be 3 January and 6 Feburary, if you’re not into too many decimal places. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [March 19, 2011, 10:47am UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/36 "2011-03-19T10:47:25Z")
> [@flatlined](#): > > I think that we need to keep this thread open…because you are trying to learn how irrational us geeks can be. > > PS.. Pi is an irrational number Er, if you’re just measuring, you won’t be able to get pi, unless you have infinite accuracy. Why? Irrational numbers can’t be expressed as fractions. When you divide circumference by diameter, that’s actually a fraction. Another thing: all fractions end up as decimals with repeated sequences, so you can’t keep dividing for long 😃 ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [March 19, 2011, 4:20pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/37 "2011-03-19T16:20:14Z")
> [@AaronX](#): > > Er, if you’re just measuring, you won’t be able to get pi, unless you have infinite accuracy. Why? Irrational numbers can’t be expressed as fractions. When you divide circumference by diameter, that’s actually a fraction. If the circumference or diameter itself is irrational, dividing the circumference by the diameter would give you an irrational number. But you’re not going to be able to take a physical, real-world measurement and get an irrational number. I find it interesting that, even though pi has been known as a special number for thousands of years, it’s only since the 1700’s that it’s been called “pi” (i.e. that the symbol π has been used). And it was only proved to be irrational in 1761. (By contrast, the ancient Greeks knew that the square root of 2 is irrational.) ---
**Author:** ![flatlined](https://avatars.discourse-cdn.com/v4/letter/f/eb9ed0/32.png) [@flatlined](https://boards.straightdope.com/u/flatlined)\ **Post date:** [March 19, 2011, 7:03pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/38 "2011-03-19T19:03:41Z")
> [@AaronX](#): > > Er, if you’re just measuring, you won’t be able to get pi, unless you have infinite accuracy. Why? Irrational numbers can’t be expressed as fractions. When you divide circumference by diameter, that’s actually a fraction. Another thing: all fractions end up as decimals with repeated sequences, so you can’t keep dividing for long 😃 You are right, of course. You can’t get good numbers with a stew can and a ruler. I usually go wrong 4 or 5 digits into the call. When I check my numbers with a calculator, my results are correct according to the data. GIGO happens:) I’ve never been good with fractions, so the first thing I do when dealing with them is convert them to decimals. I’m quite sure most of the Garbage In starts there. I’m not trying to win a Nobel prize with my scribblings, its a something to do while ignoring the hold muzak. Some people draw flowers or fill in the letters. I do long division with paper and a number 2 pencil 😃 ---
**Author:** ![Histrion](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@Histrion](https://boards.straightdope.com/u/Histrion)\ **Post date:** [March 19, 2011, 8:20pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/39 "2011-03-19T20:20:05Z")
I only have π memorized out to the “2643” myself. Used to know it a little further. **AaronX** - the limit of a series of rationals can be irrational. For instance, successive Fibonacci numbers have a ratio that converges to (1 + sqrt(5) ) / 2, a.k.a. φ, the so-called “golden ratio.” **flatlined** - I think the question’s still sort of hanging as to what exactly it is you’re dividing by what (using long division of decimals or fractions, either way) to calculate π. Are you actually drawing a big circle and dividing circumference by diameter? (If so, the two follow-up questions: are you using standard 8.5 x 11" or A4, and how are you measuring the circumference? I think that’s why some readers here might be a bit perplexed.) I actually spent some time a few weeks ago using the Pythagorean Theorem to work out how to approximate pi as a succession of perimeters of inscribed polygons in the unit circle, doubling the number of sides each time. Turns out that, as in iterative formula, it actually works out pretty nicely. Wouldn’t really work as **flatlined** ’s method, because it involves taking square roots, but if you have a calculator it converges pretty quickly: Let x\_1 = sqrt(2) (the length of one side of the inscribed square). As a first approximation, π = 2x\_1 ≈2.8284. Then, iterate, starting with i = 2: x\_i = sqrt( 1 + 0.5x\_(i-1) ) - sqrt( 1 - 0.5x\_(i-1) ) ; π ≈ (2^i)x\_i You get: x\_1 ≈ 1.414213562 π ≈ 2x\_1 ≈ 2.828427125 x\_2 ≈ .7653668647 π ≈ 4x\_2 ≈ 3.061467459 x\_3 ≈ 0.3901806440 π ≈ 8x\_3 ≈ 3.121445152 x\_4 ≈ 0.1960342807 π ≈ 16x\_4 ≈ 3.136548491 By the time you get to i = 10, your π value is accurate to the 5th decimal place. At that point the inscribed polygon has 2048 sides, each of length x\_10 ≈ 0.003. You wind up gaining about one more digit of accuracy every two steps, until eventually your calculator’s precision limits start introducing rounding errors. In other words, **flatlined** , you’re not the only one around here who does math when he’s bored. I’ve been experimenting with the arithmetic of continued fractions lately, myself. ---
**Author:** ![surrounded\_by\_literalists](https://avatars.discourse-cdn.com/v4/letter/s/8baadc/32.png) [@surrounded\_by\_literalists](https://boards.straightdope.com/u/surrounded_by_literalists)\ **Post date:** [March 19, 2011, 8:34pm UTC](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624/40 "2011-03-19T20:34:42Z")
And they say women are irrational (snicker!) [Previous page](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624.md?page=1) [Next page](https://boards.straightdope.com/t/march-14th-happy-pi-day-everyone/574624.md?page=3)