100 sided dice? [Archive] - Wizards Community

100 sided dice? [Archive] - Wizards Community

Post/Author/DateTime Post
Operu
05-31-06, 08:57 PM Okay I have always used 2 d10's to figure percentages in my games etc... But I have run into many situations where I might want to use numbers 1-100 and I was wondering if anyone could tell me which is mathematically more correct? A d100 or a set of 2 D10's one used for the tens place the others for the 1's place? I don't really know how to put it because I am very poor at math and probabilities etc... but could anyone tell me if one of these methods is MORE correct? or if they both yeild the same probabilities?

Thanks alot...

It seems to me that it would be even, both yeilding the same chances, but like I said, I stink at math. So my guess isnt really a good one.

Operu
Silverstream
05-31-06, 09:04 PM The two have the same percentages.

The d100 of course has a 1% chance for any single number.

For the two d10's... consider this.

Let's say the target number was 57. In order to get that number, you MUST roll a 5 on the first die and a 7 on the second die. No other combination will work, even a 7 on the first die and a 5 on the second (That'd be 75). So, there is 1 possible way. The way to figure probability is to take the number of ways possible (1) and divide by the number of total possible outcomes. In this case, 100 (10*10). So, 1 divided by 100 is 1%.

You cannot, however, roll 10d10 and add them together to get a number our of 100, because the odds aren't there (0% chance to get anything between 1 and 9, for example). It's when you're ADDING numbers together that the odds become skewed (2d4 does not equal 1d8, for example).
stealth_monkey
05-31-06, 09:06 PM As long as you specify which die will be the tens and which will be the units before the roll, both have identical probabilities. So if you really want a d100, feel free to buy one, but it won't be any more "correct". Technically, it will actually be slightly less accurate after a while, because since the edges are fainter, the roll will be greater affected by wear, but you won't be able to notice it
Operu
05-31-06, 09:08 PM wow, perfect answer to a question ive been wondering for a while. Thank you guys for the quick accurate responses. I appreciate it.
Archangel62
05-31-06, 09:13 PM I have a 100 sider, got it as a present from my girlfriend on our anniversary. Anyhow the only problem I've seen with it is that the plastic cover it has to protect the numbers can make it difficult to read the numbers due to the angle that they're set at. That and I'm not sure if it would stop rolling without hitting something.
Operu
05-31-06, 09:51 PM yeah, and there just seems to be something more nostalgiac about two ten-siders...
Bulletproof_Condom
05-31-06, 11:22 PM I have seen a virtual d100 that was a large d10, transparent and hollow with a smaller d10 inside it. The big one was the tens and the little one was the ones.

But yeah, if you're looking for 1-100 instead of 00-99, just read "00" as "100". The odds don't change.
__DnD4Life__
05-31-06, 11:56 PM I would stick to the 2d10s, as the d100 will take almost 3x as long to come to a complete stop. One of my DMs has one, and we stopped using it because it just took too long to roll. The sides were so small, it would roll on, and on, and on, and on,....well you get the picture. Other than that, they are exactly the same.

http://img162.imageshack.us/img162/6714/dnd4life27kp.png
Witch
06-01-06, 03:38 AM A d100 is less accurate than 2 d10s.
Archangel62
06-01-06, 03:49 AM A d100 is less accurate than 2 d10s.

That being said it can be great in times of drama, or for humor. Funnier bit involved me mentioning I had to get out the damage die and I put the 100 sider on the table while I dug for a few d12s and the groans and looks of horror were priceless. It took me a minute to realize they thought that that sucker was the damage die.
Witch
06-01-06, 03:51 AM Priceless =)
Archangel62
06-01-06, 03:58 AM Yeah, but that being said 100 siders aren't necessarily less accurate, it's just that the tables were designed with 2 D10s in mind. As a result the hundred sider throws things off more by dint of different percentage chances for things as all chances are equal, unlike those of say 2d10.
Witch
06-01-06, 04:01 AM I do believe all chances are equal in 2 d10s.

However, the technique used to create d100s leads them to being less accurate.
Ankalagon
06-01-06, 05:12 AM I have a 100 sider, got it as a present from my girlfriend on our anniversary.
Now that's a gamer :bow:

Most people would go for french restaurants and soft lighting.
blinks
06-01-06, 11:56 AM Yeah, but that being said 100 siders aren't necessarily less accurate, it's just that the tables were designed with 2 D10s in mind. As a result the hundred sider throws things off more by dint of different percentage chances for things as all chances are equal, unlike those of say 2d10.

As an earlier poster said: 2d10 gives the same output as 1d100, if you are marking the dice (or have nice 10s/1s dice).

1d100: P(n) = 1/100 for all valid n.
2d10: P(n) = Pa(int n/10) * Pb(n mod 10) = 1/10 * 1/10 = 1/100 for all valid n, where Pa(int n/10) is the probability of the 10s place showing up on the 10s dice, and Pb(n mod 10) is the probability of the 1s place showing up on the 1s dice.
revnk
06-01-06, 12:37 PM Exactly. Witch wasn't referring to the raw probability per se, but to the fact that d100s physically tend to have very small sides and to wear unevenly, which means that the chance of a number being rolled may be affected by the physical properties that cause the die to land on a particular side. In other words, over time a certain number may start coming up more often simply because the die is no longer generating a random number.

Incidentally, to clarify things for the original poster: "2d10" generally refers to a number between 2 and 20 generated by adding the results of 2 10-sided dice together. This number creates a bell curve instead of a linear curve. In a bell curve, there is a greater probability of generating mean numbers than end numbers (on 2d10, "14" is more likely than "2" or "20"). Rolling 2 10-sided dice to generate a number between 00-99 (01-00) generates a straight curve ("54" is just as likely as "17" or "86").

The original 1E DMG actually had a nice little section explaining this. It might have been one of the things Wizards could have stuck into an appendix to the 3.5 PHB, given the wide range of ages and educations that come to the hobby--and how awful the schools seem to be these days. :teach:

Hope that helps.
Archangel62
06-01-06, 01:28 PM Now that's a gamer :bow:

Most people would go for french restaurants and soft lighting.

Oh we do that too, but as we both game we also give gifts that work for us.
striderII
06-01-06, 01:34 PM That being said it can be great in times of drama, or for humor. Funnier bit involved me mentioning I had to get out the damage die and I put the 100 sider on the table while I dug for a few d12s and the groans and looks of horror were priceless. It took me a minute to realize they thought that that sucker was the damage die.

Heh. I remember quite a few years ago there was a bit in Dragon about funny/amusing quotes that a DM could say. One I'll never forget was an actual quote (rather than a supposition):

"He hits, and....I'm gonna need more dice".

I found that hilarious. :)

strider
Morka
06-01-06, 02:00 PM I use the key Random on my calculator. It gives you a random number between 0.000 and 0.999. So you can have a virtual D1000!
Witch
06-01-06, 02:19 PM I always believed software was incapable of true randomisation, though.
ArcTan
06-01-06, 02:21 PM Wow, people actually seriously use d100's? I always saw those as nothing more than a gag gift.

It's like paying money to buy an actual d2 (a plastic disc with 1 and 2 on the opposite sides) rather than just keeping a quarter around.

I've joked with my friends about selling d1's, which would be miniature little wobble things (you know, the rounded cones that wobble around on their base but always end up with the narrow end pointing upwards) that just had a "1" printed on the tip. You could then express every single numerical outcome in D&D with dice, and roll a completely superfluous "30d1" for, say, maximized spells.
hmmmm
06-01-06, 03:22 PM I would so buy one of those.
clarkvalentine
06-01-06, 03:53 PM It's like paying money to buy an actual d2 (a plastic disc with 1 and 2 on the opposite sides) rather than just keeping a quarter around.

I have several d2s - they're six-sided dice triple-numbered 1-1-1 and 2-2-2. THey're used in the Serenity RPG. :) Why not use a coin? It's just so much easier to pick up a die with a handful of other dice. "Roll a d12, a d8, and then flip a quarter."

Besides, it's cool to be able to say "I have a d2!"
Tempest Stormwind
06-01-06, 04:10 PM I always believed software was incapable of true randomisation, though.
True. It is, however, random *enough* for most intents and purposes, including much work on statistics or numerical integration in physics research. D&D, by extension, should be close enough.

I had a D100. It was effectively a golf ball with ball bearings inside to stop the motion early.

It broke.

I used, and still use, 2d10 to generate mine (though the tens digit is usually a smaller d10 with double-digit numbers on it).

If I want to scare my players, though, I have two THIRTY siders that roll far easier. I also have a six-sider that I use when teaching math to little kids with +, -, x, and / on it, with + and x showing up twice.

Put these together. ;)
The man they call Boxhead
06-01-06, 04:15 PM I have several d2s - they're six-sided dice triple-numbered 1-1-1 and 2-2-2. THey're used in the Serenity RPG. :) Why not use a coin? It's just so much easier to pick up a die with a handful of other dice. "Roll a d12, a d8, and then flip a quarter."

Besides, it's cool to be able to say "I have a d2!"

I have a couple of D3s like that, 1 2 3 twice on them. They can be fun, but really serve no particular purpose. I use them about half the time I need a D3.

I've got the infamous D100, I like to use it for random treasure rolls, generally before the game starts. I've also got a D30, which I like to use when I cheat. ;)
There's nothing quite so much fun as rolling an unmodified 30 to hit...

Mostly I just love dice...

Post/Author/DateTime	Post
Operu 05-31-06, 08:57 PM	Okay I have always used 2 d10's to figure percentages in my games etc... But I have run into many situations where I might want to use numbers 1-100 and I was wondering if anyone could tell me which is mathematically more correct? A d100 or a set of 2 D10's one used for the tens place the others for the 1's place? I don't really know how to put it because I am very poor at math and probabilities etc... but could anyone tell me if one of these methods is MORE correct? or if they both yeild the same probabilities? Thanks alot... It seems to me that it would be even, both yeilding the same chances, but like I said, I stink at math. So my guess isnt really a good one. Operu
Silverstream 05-31-06, 09:04 PM	The two have the same percentages. The d100 of course has a 1% chance for any single number. For the two d10's... consider this. Let's say the target number was 57. In order to get that number, you MUST roll a 5 on the first die and a 7 on the second die. No other combination will work, even a 7 on the first die and a 5 on the second (That'd be 75). So, there is 1 possible way. The way to figure probability is to take the number of ways possible (1) and divide by the number of total possible outcomes. In this case, 100 (10*10). So, 1 divided by 100 is 1%. You cannot, however, roll 10d10 and add them together to get a number our of 100, because the odds aren't there (0% chance to get anything between 1 and 9, for example). It's when you're ADDING numbers together that the odds become skewed (2d4 does not equal 1d8, for example).
stealth_monkey 05-31-06, 09:06 PM	As long as you specify which die will be the tens and which will be the units before the roll, both have identical probabilities. So if you really want a d100, feel free to buy one, but it won't be any more "correct". Technically, it will actually be slightly less accurate after a while, because since the edges are fainter, the roll will be greater affected by wear, but you won't be able to notice it
Operu 05-31-06, 09:08 PM	wow, perfect answer to a question ive been wondering for a while. Thank you guys for the quick accurate responses. I appreciate it.
Archangel62 05-31-06, 09:13 PM	I have a 100 sider, got it as a present from my girlfriend on our anniversary. Anyhow the only problem I've seen with it is that the plastic cover it has to protect the numbers can make it difficult to read the numbers due to the angle that they're set at. That and I'm not sure if it would stop rolling without hitting something.
Operu 05-31-06, 09:51 PM	yeah, and there just seems to be something more nostalgiac about two ten-siders...
Bulletproof_Condom 05-31-06, 11:22 PM	I have seen a virtual d100 that was a large d10, transparent and hollow with a smaller d10 inside it. The big one was the tens and the little one was the ones. But yeah, if you're looking for 1-100 instead of 00-99, just read "00" as "100". The odds don't change.
__DnD4Life__ 05-31-06, 11:56 PM	I would stick to the 2d10s, as the d100 will take almost 3x as long to come to a complete stop. One of my DMs has one, and we stopped using it because it just took too long to roll. The sides were so small, it would roll on, and on, and on, and on,....well you get the picture. Other than that, they are exactly the same. http://img162.imageshack.us/img162/6714/dnd4life27kp.png
Witch 06-01-06, 03:38 AM	A d100 is less accurate than 2 d10s.
Archangel62 06-01-06, 03:49 AM	A d100 is less accurate than 2 d10s. That being said it can be great in times of drama, or for humor. Funnier bit involved me mentioning I had to get out the damage die and I put the 100 sider on the table while I dug for a few d12s and the groans and looks of horror were priceless. It took me a minute to realize they thought that that sucker was the damage die.
Witch 06-01-06, 03:51 AM	Priceless =)
Archangel62 06-01-06, 03:58 AM	Yeah, but that being said 100 siders aren't necessarily less accurate, it's just that the tables were designed with 2 D10s in mind. As a result the hundred sider throws things off more by dint of different percentage chances for things as all chances are equal, unlike those of say 2d10.
Witch 06-01-06, 04:01 AM	I do believe all chances are equal in 2 d10s. However, the technique used to create d100s leads them to being less accurate.
Ankalagon 06-01-06, 05:12 AM	I have a 100 sider, got it as a present from my girlfriend on our anniversary. Now that's a gamer :bow: Most people would go for french restaurants and soft lighting.
blinks 06-01-06, 11:56 AM	Yeah, but that being said 100 siders aren't necessarily less accurate, it's just that the tables were designed with 2 D10s in mind. As a result the hundred sider throws things off more by dint of different percentage chances for things as all chances are equal, unlike those of say 2d10. As an earlier poster said: 2d10 gives the same output as 1d100, if you are marking the dice (or have nice 10s/1s dice). 1d100: P(n) = 1/100 for all valid n. 2d10: P(n) = Pa(int n/10) * Pb(n mod 10) = 1/10 * 1/10 = 1/100 for all valid n, where Pa(int n/10) is the probability of the 10s place showing up on the 10s dice, and Pb(n mod 10) is the probability of the 1s place showing up on the 1s dice.
revnk 06-01-06, 12:37 PM	Exactly. Witch wasn't referring to the raw probability per se, but to the fact that d100s physically tend to have very small sides and to wear unevenly, which means that the chance of a number being rolled may be affected by the physical properties that cause the die to land on a particular side. In other words, over time a certain number may start coming up more often simply because the die is no longer generating a random number. Incidentally, to clarify things for the original poster: "2d10" generally refers to a number between 2 and 20 generated by adding the results of 2 10-sided dice together. This number creates a bell curve instead of a linear curve. In a bell curve, there is a greater probability of generating mean numbers than end numbers (on 2d10, "14" is more likely than "2" or "20"). Rolling 2 10-sided dice to generate a number between 00-99 (01-00) generates a straight curve ("54" is just as likely as "17" or "86"). The original 1E DMG actually had a nice little section explaining this. It might have been one of the things Wizards could have stuck into an appendix to the 3.5 PHB, given the wide range of ages and educations that come to the hobby--and how awful the schools seem to be these days. :teach: Hope that helps.
Archangel62 06-01-06, 01:28 PM	Now that's a gamer :bow: Most people would go for french restaurants and soft lighting. Oh we do that too, but as we both game we also give gifts that work for us.
striderII 06-01-06, 01:34 PM	That being said it can be great in times of drama, or for humor. Funnier bit involved me mentioning I had to get out the damage die and I put the 100 sider on the table while I dug for a few d12s and the groans and looks of horror were priceless. It took me a minute to realize they thought that that sucker was the damage die. Heh. I remember quite a few years ago there was a bit in Dragon about funny/amusing quotes that a DM could say. One I'll never forget was an actual quote (rather than a supposition): "He hits, and....I'm gonna need more dice". I found that hilarious. :) strider
Morka 06-01-06, 02:00 PM	I use the key Random on my calculator. It gives you a random number between 0.000 and 0.999. So you can have a virtual D1000!
Witch 06-01-06, 02:19 PM	I always believed software was incapable of true randomisation, though.
ArcTan 06-01-06, 02:21 PM	Wow, people actually seriously use d100's? I always saw those as nothing more than a gag gift. It's like paying money to buy an actual d2 (a plastic disc with 1 and 2 on the opposite sides) rather than just keeping a quarter around. I've joked with my friends about selling d1's, which would be miniature little wobble things (you know, the rounded cones that wobble around on their base but always end up with the narrow end pointing upwards) that just had a "1" printed on the tip. You could then express every single numerical outcome in D&D with dice, and roll a completely superfluous "30d1" for, say, maximized spells.
hmmmm 06-01-06, 03:22 PM	I would so buy one of those.
clarkvalentine 06-01-06, 03:53 PM	It's like paying money to buy an actual d2 (a plastic disc with 1 and 2 on the opposite sides) rather than just keeping a quarter around. I have several d2s - they're six-sided dice triple-numbered 1-1-1 and 2-2-2. THey're used in the Serenity RPG. :) Why not use a coin? It's just so much easier to pick up a die with a handful of other dice. "Roll a d12, a d8, and then flip a quarter." Besides, it's cool to be able to say "I have a d2!"
Tempest Stormwind 06-01-06, 04:10 PM	I always believed software was incapable of true randomisation, though. True. It is, however, random enough for most intents and purposes, including much work on statistics or numerical integration in physics research. D&D, by extension, should be close enough. I had a D100. It was effectively a golf ball with ball bearings inside to stop the motion early. It broke. I used, and still use, 2d10 to generate mine (though the tens digit is usually a smaller d10 with double-digit numbers on it). If I want to scare my players, though, I have two THIRTY siders that roll far easier. I also have a six-sider that I use when teaching math to little kids with +, -, x, and / on it, with + and x showing up twice. Put these together. ;)
The man they call Boxhead 06-01-06, 04:15 PM	I have several d2s - they're six-sided dice triple-numbered 1-1-1 and 2-2-2. THey're used in the Serenity RPG. :) Why not use a coin? It's just so much easier to pick up a die with a handful of other dice. "Roll a d12, a d8, and then flip a quarter." Besides, it's cool to be able to say "I have a d2!" I have a couple of D3s like that, 1 2 3 twice on them. They can be fun, but really serve no particular purpose. I use them about half the time I need a D3. I've got the infamous D100, I like to use it for random treasure rolls, generally before the game starts. I've also got a D30, which I like to use when I cheat. ;) There's nothing quite so much fun as rolling an unmodified 30 to hit... Mostly I just love dice...