# 17-sided dice?? **URL:** \ **Category:** The Game Room\ **Created:** [November 7, 2008, 1:31am UTC](https://boards.straightdope.com/t/17-sided-dice/471573 "2008-11-07T01:31:00Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 7, 2008, 1:31am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/1 "2008-11-07T01:31:00Z")
I keep hearing references to these. Is it a joke that’s become a gaming meme, or is it for real? Why would anyone need to roll a random number from 1 to 17? ---
**Author:** ![Wargamer](https://avatars.discourse-cdn.com/v4/letter/w/df705f/32.png) [@Wargamer](https://boards.straightdope.com/u/Wargamer)\ **Post date:** [November 7, 2008, 1:35am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/2 "2008-11-07T01:35:31Z")
No such thing as a 17 sided die. If you need a random number between 1 and 17, just roll a d34 and divide by 2. ---
**Author:** ![Shamozzle](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shamozzle](https://boards.straightdope.com/u/Shamozzle)\ **Post date:** [November 7, 2008, 1:48am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/3 "2008-11-07T01:48:45Z")
Are we not bound by the five platonic solids if we are to have even expectations for any result? ---
**Author:** ![Hoopy\_Frood](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hoopy_frood/32/8452_2.png) [@Hoopy\_Frood](https://boards.straightdope.com/u/Hoopy_Frood)\ **Post date:** [November 7, 2008, 1:51am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/4 "2008-11-07T01:51:05Z")
> [@Wargamer](#): > > No such thing as a 17 sided die. If you need a random number between 1 and 17, just roll a d34 and divide by 2. Bah, I prefer to use my d18 and just ignore 18. ---
**Author:** ![Duke](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@Duke](https://boards.straightdope.com/u/Duke)\ **Post date:** [November 7, 2008, 1:51am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/5 "2008-11-07T01:51:51Z")
> [@Shamozzle](#): > > Are we not bound by the five platonic solids if we are to have even expectations for any result? I rolled my d10 and it said no. ---
**Author:** ![Hoopy\_Frood](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hoopy_frood/32/8452_2.png) [@Hoopy\_Frood](https://boards.straightdope.com/u/Hoopy_Frood)\ **Post date:** [November 7, 2008, 1:56am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/6 "2008-11-07T01:56:16Z")
I have a friend with one of those triangular prism 5-siders. ---
**Author:** ![Hoopy\_Frood](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hoopy_frood/32/8452_2.png) [@Hoopy\_Frood](https://boards.straightdope.com/u/Hoopy_Frood)\ **Post date:** [November 7, 2008, 1:58am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/7 "2008-11-07T01:58:54Z")
Of course, with my typical luck I roll a d1 and it comes up 0. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [November 7, 2008, 2:07am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/8 "2008-11-07T02:07:39Z")
> [@Shamozzle](#): > > Are we not bound by the five platonic solids if we are to have even expectations for any result? I routinely carry around several d2s in my pocket. Though I usually use them to buy things. ---
**Author:** ![Shamozzle](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shamozzle](https://boards.straightdope.com/u/Shamozzle)\ **Post date:** [November 7, 2008, 2:48am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/9 "2008-11-07T02:48:50Z")
> [@Duke](#): > > I rolled my d10 and it said no. Right, right. I suppose that while the overall shape of a d10 is not symmetrical in the platonic solid sense, each face or group of faces exhibits symmetry. Or something like that… ---
**Author:** ![glee](https://avatars.discourse-cdn.com/v4/letter/g/b5a626/32.png) [@glee](https://boards.straightdope.com/u/glee)\ **Post date:** [November 7, 2008, 10:49am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/10 "2008-11-07T10:49:21Z")
> [@Lumpy](#): > > I keep hearing references to these. Is it a joke that’s become a gaming meme, or is it for real? Why would anyone need to roll a random number from 1 to 17? Can you give us such a reference? Having roleplayed for decades, I’m still using the same d4, d6, d8, d12 and d20 (as Shamozzle points out, these are the five Platonic Solids). There is an irregualr-shaped d10, because two of them are so useful for generating % die rolls. I’ve seen d30 and d100 advertised, but never used. There’s absolutely no point in a d17. If a DM has a list of 17 items, they can either weight it, or add 3 more things. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [November 7, 2008, 11:05am UTC](https://boards.straightdope.com/t/17-sided-dice/471573/11 "2008-11-07T11:05:00Z")
> [@Shamozzle](#): > > Are we not bound by the five platonic solids if we are to have even expectations for any result? No, certain strict requirements for entry into the ‘platonic solid club’ have no bearing on whether an object will perform well as a randomizer: - That the faces must have edges the same length and angles the same size. - That the same number of faces must meet at every vertex of the solid. The old ‘spindle d10s’ I remember illustrate how to get a decent die without worrying about platonic solidity - just make every face the same shape, and construct the solid so that it’s rotationally and reflectionally symmetrical. For those d10s, the faces were more or less elongated triangles, with five faces meeting at the extreme corners, (rounded off so they weren’t too pokey,) and three faces meeting at vertices along the borderline between the ‘south’ and ‘north’ side as it were. ---
**Author:** ![Hoopy\_Frood](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hoopy_frood/32/8452_2.png) [@Hoopy\_Frood](https://boards.straightdope.com/u/Hoopy_Frood)\ **Post date:** [November 7, 2008, 1:01pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/12 "2008-11-07T13:01:07Z")
> [@chrisk](#): > > No, certain strict requirements for entry into the ‘platonic solid club’ have no bearing on whether an object will perform well as a randomizer: > > - That the faces must have edges the same length and angles the same size. > - That the same number of faces must meet at every vertex of the solid. > > The old ‘spindle d10s’ I remember illustrate how to get a decent die without worrying about platonic solidity - just make every face the same shape, and construct the solid so that it’s rotationally and reflectionally symmetrical. For those d10s, the faces were more or less elongated triangles, with five faces meeting at the extreme corners, (rounded off so they weren’t too pokey,) and three faces meeting at vertices along the borderline between the ‘south’ and ‘north’ side as it were. And my aforementioned d5. Here’s what one looks like: [http://paizo.com/image/product/catalog/CHX/CHXXT0505\_500.jpeg](http://paizo.com/image/product/catalog/CHX/CHXXT0505_500.jpeg) Perfectly randomized, yet you’d never guess by looking at the thing. (And yes, I’m using the term “perfect” loosely here, since most dice have some sort of slight bias introduced due to the uncontrollable imperfections inherent in manufacturing anything. Though for most people’s purposes they’ll never notice it.) ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 7, 2008, 1:50pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/13 "2008-11-07T13:50:39Z")
> [@glee](#): > > Can you give us such a reference? A simple Google of “17-sided dice” turned up: > [@Google](#): > > This is just like Dungeons and Dragons, but without all the weird 17-sided dice and the lack of showering for three days in your mother’s basement with your … > > Turn-based RPG’s might be nostalgic but they’re a short step away from sitting around a table in a dark room rolling a 17-sided dice. … > > (Yes, I bought a lot of Cheapass games…) If I lack any of the components, I can find them easily enough. Well, except for those 17-sided dice… 😉 … > > Did you also play with 17-sided dice in your mom’s basement on Friday nights? I just want to cry. (I keed! I keed! Well, except for that Cobol thing. … > > Suppose that a pair of 17-sided dice is rolled five times. What is the probability that the sum of the faces is even? Is the answer the same as for the … Apparently there was some really archaic gaming system that called for them, unless as I asked earlier if this is really just a long-running joke. ---
**Author:** ![glee](https://avatars.discourse-cdn.com/v4/letter/g/b5a626/32.png) [@glee](https://boards.straightdope.com/u/glee)\ **Post date:** [November 7, 2008, 2:21pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/14 "2008-11-07T14:21:11Z")
> [@Lumpy](#): > > A simple Google of “17-sided dice” turned up:Apparently there was some really archaic gaming system that called for them, unless as I asked earlier if this is really just a long-running joke. Given the reference to Cobol (which I learnt out of a book in 1972 :eek:) and the smilie, it’s definitely a joke. ---
**Author:** ![Dead\_Cat](https://avatars.discourse-cdn.com/v4/letter/d/9fc29f/32.png) [@Dead\_Cat](https://boards.straightdope.com/u/Dead_Cat)\ **Post date:** [November 7, 2008, 2:21pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/15 "2008-11-07T14:21:36Z")
I have a game called Card Dice which has supposedly fair 13-sided dice. ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [November 7, 2008, 2:28pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/16 "2008-11-07T14:28:11Z")
> [@Lumpy](#): > > A simple Google of “17-sided dice” turned up:Apparently there was some really archaic gaming system that called for them, unless as I asked earlier if this is really just a long-running joke. It is an old joke. I am a ‘really archaic gaming system’ and the 17 siders have only existed as computer/calculator programs and I have used a d17 and almost any other Dnnn you could think of. I needed the D17 for a short \*Deck of Many Things \*one time. We use a D20 and just rerolled if over 17. I also use Excel often to construct any oddball dieroll needed. Example: =INT(RAND()\*17)+1 gives you 1 to 17. Hi **Glee** , Speaking of ‘really archaic gaming system’. He’s another. 😉 Jim ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [November 7, 2008, 2:38pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/17 "2008-11-07T14:38:48Z")
17-siders are used to randomly determine the age of Minor DNPCs (dependent non-player characters, like Aunt May in Spiderman or Ando in Heroes). ---
**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\ **Post date:** [November 7, 2008, 4:01pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/18 "2008-11-07T16:01:13Z")
> [@glee](#): > > I’ve seen d30 and d100 advertised, but never used. I bought a few d30s (two red and one clear, as I remember) from a gaming store back when I was in high school, because they were just neat. To get some use out of them, I designed my own RPG around 'em. Okay, technically not an RPG, just a system of one-on-one arena combat with six character classes, but I was pretty pleased with it. Reaching back into my hazy memory, rolling those high numbers could completely reverse the direction of a fight; a 29 was a “minor” and a 30 a “major”. As in, a Martial Artist rolling a 29 scored a “minor break”, a finger or toe, while a 30 would be a “major break”, an arm or leg. A Fencer rolling 29 scored a “minor pierce”, a fleshy area such as an arm or shoulder, while a 30 “major pierce” scored an organ, spleen or liver or the like. There was “minor/major sever” for fingers/limbs, “minor/major poison” for assassins…I was pretty pleased with it. Anyway, I’m rambling, hijack over. Someone at one time in history actually got use out of d30s. heh. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [November 7, 2008, 4:07pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/19 "2008-11-07T16:07:57Z")
Is a d30 a “platonic solid?” I’ve seen them advertised, and I think maybe _once_ I saw a reference to a D30 in some roleplaying book, but that’s about it. They look like [this.](http://www.helps4teachers.com/shop/images/30%20sided%20dice.jpg) And it seems [Chessex.com](http://www.chessex.com/Dice/Dice_Home.htm) has several other “non-traditional” dice, like a 3, 5, 7, 14, 16, 24, the aforementioned 30, and 34. And 100…but a 100-sided die is just a sphere with numbers on it…you NEVER get it to perfectly have one number facing up. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [November 7, 2008, 4:31pm UTC](https://boards.straightdope.com/t/17-sided-dice/471573/20 "2008-11-07T16:31:32Z")
> [@Hoopy\_Frood](#): > > And my aforementioned d5. Here’s what one looks like: [http://paizo.com/image/product/catalog/CHX/CHXXT0505\_500.jpeg](http://paizo.com/image/product/catalog/CHX/CHXXT0505_500.jpeg) > > Perfectly randomized, yet you’d never guess by looking at the thing. (And yes, I’m using the term “perfect” loosely here, since most dice have some sort of slight bias introduced due to the uncontrollable imperfections inherent in manufacturing anything. Though for most people’s purposes they’ll never notice it.) It’s hard to tell for sure based on that picture, but I think that there’s an subjective difference between a non-platonic die where all the faces are symmetrical, and a die where obviously dissimilar faces are ‘perfectly randomized’. Which leads naturally to the question - what numbers of faces could a solid be made in with all faces symmetrical - obviously the spindle approach will work for any even number, though a d100 made that way would look pretty weird. What about a d9 or a d15? Could prime numbers ever be made symmetrical this way? [Next page](https://boards.straightdope.com/t/17-sided-dice/471573.md?page=2)