# What's your favourite constant? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [April 21, 2006, 1:22am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559 "2006-04-21T01:22:42Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![QuickSilver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quicksilver/32/7832_2.png) [@QuickSilver](https://boards.straightdope.com/u/QuickSilver)\ **Post date:** [April 21, 2006, 1:22am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/1 "2006-04-21T01:22:42Z")
Share your favourite Constant and associated formula. I know it’s probably too easy and totally not essoteric but I’ll have to go with _pi_ (22/7). Formuli: Surface Area = 4(pi)r**2 Volume = 4/3(pi)r**3 \*yeah, feelin’ kinda dorky tonight. ---
**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\ **Post date:** [April 21, 2006, 1:26am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/2 "2006-04-21T01:26:29Z")
Avogadro’s number: 6.023 x 10[sup]23[/sup] It’s one of the few things I remember from school chemistry. ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [April 21, 2006, 1:38am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/3 "2006-04-21T01:38:05Z")
As a chemist, I should probably choose Avogardro’s number. But I’m not. I’m thinking something more along the lines of Planck’s constant. ---
**Author:** ![El\_Perro\_Fumando](https://avatars.discourse-cdn.com/v4/letter/e/e9c0ed/32.png) [@El\_Perro\_Fumando](https://boards.straightdope.com/u/El_Perro_Fumando)\ **Post date:** [April 21, 2006, 1:43am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/4 "2006-04-21T01:43:23Z")
e, and with it the associated formula A=Pe[sup]rt[/sup] ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [April 21, 2006, 1:47am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/5 "2006-04-21T01:47:26Z")
[symbol]w[/symbol], the probability that a randomly chosen computer program will halt on a randomly chosen input. The beautiful thing about it is that there’s no way to know whether the nth bit of [symbol]w[/symbol] is 0 or 1 without taking its value as an axiom. ---
**Author:** ![Lionne](https://avatars.discourse-cdn.com/v4/letter/l/8e8cbc/32.png) [@Lionne](https://boards.straightdope.com/u/Lionne)\ **Post date:** [April 21, 2006, 2:00am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/6 "2006-04-21T02:00:00Z")
Does A2 +B2 =C2 count? ---
**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:** [April 21, 2006, 2:14am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/7 "2006-04-21T02:14:13Z")
> [@QuickSilver](#): > > I know it’s probably too easy and totally not essoteric but I’ll have to go with _pi_ (22/7). Okay, as long as you don’t hold the irrational belief that pi is _exactly_ 22/7. I’m gonna go with gamma, a.k.a. [Euler’s constant](http://primes.utm.edu/glossary/page.php/Gamma.html). ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [April 21, 2006, 2:42am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/8 "2006-04-21T02:42:01Z")
Planck’s Constant. Mostly because of physics class: the teacher put some equation on the board (that included it) and asked what we would do to increase the final result. I raised my hand and said we should increase Planck’s Constant. I’m also a fan of Euler’s Formula: e^(i(pi)) + 1 = 0 ---
**Author:** ![Sattua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sattua/32/11906_2.png) [@Sattua](https://boards.straightdope.com/u/Sattua)\ **Post date:** [April 21, 2006, 3:22am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/9 "2006-04-21T03:22:09Z")
Chemistry was a long time ago, but R. As in, PV = nRT. Pee Vee Nert. ---
**Author:** ![Rhiannon8404](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rhiannon8404/32/17929_2.png) [@Rhiannon8404](https://boards.straightdope.com/u/Rhiannon8404)\ **Post date:** [April 21, 2006, 3:24am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/10 "2006-04-21T03:24:15Z")
> [@El Perro Fumando](#): > > e, and with it the associated formula A=Pe[sup]rt[/sup] I was going to say this! I’m especially fond the continuous compounding formula, although I know it as FV = Pe[sup]rt[/sup]. \ ---
**Author:** ![Civil\_Guy](https://avatars.discourse-cdn.com/v4/letter/c/d78d45/32.png) [@Civil\_Guy](https://boards.straightdope.com/u/Civil_Guy)\ **Post date:** [April 21, 2006, 3:36am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/11 "2006-04-21T03:36:16Z")
…but the Bible says that pi = 3, exactly… what? No, honest, there are a couple places where it says a particular vessel was built 7 cubits across and 21 cubits around (or something like that.) Anyhow, everyone knows that 355/113 is a lot closer to pi than 22/7, right? That said, I’m going to put in a good word for the Fibonacci series. Oh, and fractals. Cool and more cool, down to the tiniest detail. ---
**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\ **Post date:** [April 21, 2006, 6:33am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/12 "2006-04-21T06:33:31Z")
e, as immortalised by what Feynman called “the jewel of mathematics”, this equation: e^(i \* pi) + 1 = 0 ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [April 21, 2006, 6:46am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/13 "2006-04-21T06:46:28Z")
If you feel like you don’t know enough to make a decision, learn about some [mathematical](http://en.wikipedia.org/wiki/Mathematical_constant) and [physical](http://en.wikipedia.org/wiki/Physical_constants) constants… Personally, I think phi, the “golden ratio” is pretty cool. It’s like a little acrobat that can twist itself up in strange ways. Pi is too popular to be my favorite, I can’t just follow the crowd. As for physical constants, I really like the sound of “epsilon-nought” even though my physics teacher always calls it “e-zero” (which pisses me off slightly because it’s not actually an e, it’s an epsilon) By the way, there are far too many things that are the letter e, or something similar. There’s e=2.71828…, E for electric field, epsilon-nought, capital epsilon for emf, E for energy, and probably something else I’m forgetting. And don’t even get me _started_ on volume, velocity, and voltage. Um, Sorry for the hijack. ---
**Author:** ![MrJackboots](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MrJackboots](https://boards.straightdope.com/u/MrJackboots)\ **Post date:** [April 21, 2006, 8:58am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/14 "2006-04-21T08:58:16Z")
Men will be stupid. Women will be crazy. Constant as anything else here. ---
**Author:** ![Mbossa](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@Mbossa](https://boards.straightdope.com/u/Mbossa)\ **Post date:** [April 21, 2006, 10:00am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/15 "2006-04-21T10:00:45Z")
I’m a fan of [Graham’s Number](http://www.everything2.com/index.pl?node_id=752584). It’s pretty big. There’s also [Legendre’s Constant](http://mathworld.wolfram.com/LegendresConstant.html). A rather fancy name for what is ultimately 1. > [@ultrafilter](#): > > w, the probability that a randomly chosen computer program will halt on a randomly chosen input. The beautiful thing about it is that there’s no way to know whether the nth bit of w is 0 or 1 without taking its value as an axiom. That’s another one I like (if anyone’s interested, it’s also called Chaitin’s constant, which is a bit more googleable). Why settle for a constant that’s merely transcendental when you can pick one that’s uncomputable? I’d like to go a step further and pick an _undefinable_ constant. It should be an easy task, since there are “infinitely more” undefinable numbers than definable ones, but oddly enough nobody seems to have defined any. ---
**Author:** ![Nancarrow](https://avatars.discourse-cdn.com/v4/letter/n/c37758/32.png) [@Nancarrow](https://boards.straightdope.com/u/Nancarrow)\ **Post date:** [April 21, 2006, 11:23am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/16 "2006-04-21T11:23:28Z")
I was gonna pick Chaitin’s constant, but it’s no fun being third. So I will pick my next favourite constant. 8.5 ---
**Author:** ![cactus\_waltz](https://avatars.discourse-cdn.com/v4/letter/c/74df32/32.png) [@cactus\_waltz](https://boards.straightdope.com/u/cactus_waltz)\ **Post date:** [April 21, 2006, 11:30am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/17 "2006-04-21T11:30:16Z")
I came to say squared a + squared b equals sqaured c, but it was done. So I got nothing. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [April 21, 2006, 11:47am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/18 "2006-04-21T11:47:25Z")
I read the thread title as ‘consonant’, and I was all ready to read some phonemic geekery and support the /ch/ in ‘loch’ and ‘TeX’. Oh, well. I like [1729](http://en.wikipedia.org/wiki/1729_%28number%29), myself. It isn’t useful, it doesn’t have to be, it’s just neat. I also like [39](http://en.wikipedia.org/wiki/39_%28number%29) for this reason: > [@](#): > > According to David Wells in The Penguin Dictionary of Curious and Interesting Numbers, 39 is the smallest mathematically uninteresting number. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [April 21, 2006, 11:50am UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/19 "2006-04-21T11:50:03Z")
This one isn’t a true constant. But I very definitely remember reading in a math textbook that Beta was a constant, which would express the ratio of ‘diagonal to perimeter’ in a rectangle. Never been able to find that book, but I do wonder if it was supposed to be a critical thinking exercise or something. Of course, I didn’t realize why it was false until a long time later. (Partly because it seemed to fit so nicely with the derivation of pi.) [sub]of course, depending on the proportions of the rectangle, that ratio can range anywhere from the square root of one-eighth, (just over 0.35) to approach 0.5 but never actually reach it without the rectangle turning into a line.[/sub] ---
**Author:** ![glee](https://avatars.discourse-cdn.com/v4/letter/g/b5a626/32.png) [@glee](https://boards.straightdope.com/u/glee)\ **Post date:** [April 21, 2006, 12:03pm UTC](https://boards.straightdope.com/t/whats-your-favourite-constant/353559/20 "2006-04-21T12:03:04Z")
> [@Dervorin](#): > > e, as immortalised by what Feynman called “the jewel of mathematics”, this equation: > > e^(i \* pi) + 1 = 0 Yes, that’s the one. Two irrationals, one imaginary number and it all rounds off perfectly?! :eek: (I think this was Euler?) [Next page](https://boards.straightdope.com/t/whats-your-favourite-constant/353559.md?page=2)