Polyhedral dice numbering conventions

[Thalain]

The most commonly used d20 convention uses "odd" and "even" hemispheres, with opposites adding to n+1 and the 1/20 in the middle of their hemisphere. 1 is surrounded by 7/13/19 and 20, accordingly, by 2/8/14. With the 20 on top, one of the most common ring configurations, clockwise, is 2,18,4,14,6,16,8,10,12.

This seems to be the setup that allows for least fudging by a player who can control rolling speed to make a certain section of the die come up more often. It spreads out the highest and lowest five numbers quite well. The pattern also makes it easy to instantly spot a player using the novelty cheat die with two 20s and no 1 - the fake 20 is surrounded by all odd numbers.

Magic's spindown life counters do not follow this pattern of course - they are not intended to be rolled as randomizer D20s and have their numbers in a spiraling pattern around the die with opposite faces typically not adding up to 21. Beware of players using them in campaigns - if they can control speed and bounce, a dexterous player can make them roll 11+ with high reliability.

 

[tankenka]

Lols! I didn't either until it was pointed out! *falls over laughing* 2004 O.O! I'm only 8 YEARS late, hahaha ~ well, on the flip side, it prompted me to write something concrete for the RPG I'm designing. Between research, sleep, and getting myself outside to train ~ there's little motivation left to hash out such detail.

Thanks for a few good laughs in the newest replies, and also for the very informative post from Thalain. Had to re-read it a couple times (just to wrap my brain around it... I'm not terribly mathematically inclined).

 

[tcm3646]

Up until the early 90's, all of my d20's added up to 21, but around then everything started to change...

I know this is 17 years later and you probably won't notice this, but yes they had dice that follow that rule, however in 1993, Magic: the Gathering came out and the dice they use for life counters, the numbers are in a sequential spiral from bottom to top and top to bottom.

 

[tcm3646]

The most commonly used d20 convention uses "odd" and "even" hemispheres, with opposites adding to n+1 and the 1/20 in the middle of their hemisphere. 1 is surrounded by 7/13/19 and 20, accordingly, by 2/8/14. With the 20 on top, one of the most common ring configurations, clockwise, is 2,18,4,14,6,16,8,10,12.

This seems to be the setup that allows for least fudging by a player who can control rolling speed to make a certain section of the die come up more often. It spreads out the highest and lowest five numbers quite well. The pattern also makes it easy to instantly spot a player using the novelty cheat die with two 20s and no 1 - the fake 20 is surrounded by all odd numbers.

Magic's spindown life counters do not follow this pattern of course - they are not intended to be rolled as randomizer D20s and have their numbers in a spiraling pattern around the die with opposite faces typically not adding up to 21. Beware of players using them in campaigns - if they can control speed and bounce, a dexterous player can make them roll 11+ with high reliability.

Just saw this, thank you for the more detailed explanation

 

[aramis erak]

Up until the early 90's, all of my d20's added up to 21, but around then everything started to change...

Most d20's did once the 1-20 numbering hit; then, MTG introduced the spindowns, which are set up so the adjacent numbers are on adjacent sides. Spindowns are decidedly unfair as d20's.

Plus, in the 90's, a dozen new companies started pumping out dice, and Gamscience's pattern was under copyright. Chessex didn't note the copyright on theirs.

I don't know who provided the mini-20's to FGU and Threshold in the 80's. (I loved the sharp edged mini-20's. Still do. But I wish they'd used harder plastic.)