
Das Bier |

No, actually. A d20 is a logical geometric hedron built outwards from a d12. I saw my geometry professor build one...basically you inset toothpicks at the 'corners' of the d12, and they become the 'faces' of the d20.
d10's are made by taking the 'middle band' of the d20 and compressing them down to too small to be rolled on.

Terquem |
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In extreme cases the game can be played without polyhedrons of any kind...
1979 -
For a period in 1979, TSR experienced a dice shortage. Basic sets published during this time frame came with two sheets of numbered cutout cardstock chits that functioned in lieu of dice, along with a coupon for ordering dice from TSR.[6] The rulebook also included a brief sample dungeon with a full-page map. Starting with the fourth printing in 1978, the two booklets of maps, encounter tables, and treasure lists were replaced with the module B1 In Search of the Unknown;[2] printings six through eleven (1979–1982) featured the module B2 The Keep on the Borderlands instead.[2]
- Wikipedia article "D&D Basic Set"

Snowblind |

If we want to get super technical, you can generate a random number that follows the desired probability curve to within an arbitrary level of precision with any source of randomness, so long as the probabilistic behavior of the source of randomness is known.
As a vaguely practical example, you can use a coin to generate a d20. {N} coin flips gets you {N} digits of a base 2 number, so you can simulate a d32(or a d10000b2) with 5 coin flips. d32, reroll anything over 20 is equivalent to a d20.
Huh. We just use the "guess a number plus roll-over" game.
GM: "Choose a number between 1-20." Mentally chooses seven.
Player: "Fifteen."
GM: "Fifteen plus seven is twenty-two. You rolled a two."
I would genuinely be interested in how "random" that would tend to be. My intuition says that certain numbers would be picked much more often than others, because humans are terrible random number generators and think nonsensical things like (for example) that certain numbers are more "random" than others.

thejeff |
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If we want to get super technical, you can generate a random number that follows the desired probability curve to within an arbitrary level of precision with any source of randomness, so long as the probabilistic behavior of the source of randomness is known.
As a vaguely practical example, you can use a coin to generate a d20. {N} coin flips gets you {N} digits of a base 2 number, so you can simulate a d32(or a d10000b2) with 5 coin flips. d32, reroll anything over 20 is equivalent to a d20.
Tacticslion wrote:I would genuinely be interested in how "random" that would tend to be. My intuition says that certain numbers would be picked much more often than others, because humans are terrible random number generators and think nonsensical things like (for example) that certain numbers are more "random" than others.Huh. We just use the "guess a number plus roll-over" game.
GM: "Choose a number between 1-20." Mentally chooses seven.
Player: "Fifteen."
GM: "Fifteen plus seven is twenty-two. You rolled a two."
I suspect the individual numbers chosen aren't very random, but having 2 people doing it probably helps a lot.

thejeff |
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It doesn't work like that. The moment you have one determistic event in the mix the end result will never be random.
Well, that in the simplest sense is obviously false.
But yeah, not really random. Better pseudo-randomness than one person doing it, even if he's trying to be random (not cheating, essentially). More closely approximating a real random spread.

thejeff |
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No, it's not.
A determistic system can not produce random results. So the moment any part of your system to generate random numerous is deterministc, it incapable of producing actually random numbers.
Exactly. Just like the computer random number generator here. Or pretty much anywhere else. (unless you've got actual hardware observing some kind of real randomness.)
However, there are better and worse forms of pseudo-randomness.

Distant Scholar |

No, it's not.
A determistic system can not produce random results. So the moment any part of your system to generate random numerous is deterministc, it incapable of producing actually random numbers.
This is completely, and utterly, false. Sorry.
If all of it is deterministic, then there is no randomness, but even a little randomness will usually make it random (with some distribution).Don't make me break out my math Ph.D. thesis.