Common questions about Dice notation

Short answers, pulled from the story.

When did dice notation become standardized in role-playing games?

The standardization of dice notation began in 1975 when Ted Johnstone published an article titled Dice as Random Number Generators in the fanzine Alarums & Excursions. This system used the letter d to separate the number of dice from the number of sides, creating expressions like 3d6 to mean roll three six-sided dice. By 1979, Gary Gygax had adopted this notation as the standard in the first edition of Advanced Dungeons & Dragons.

What does the letter d represent in dice notation?

In standard dice notation, the letter d stands for die or dice and is followed by the number of faces on the die. The faces are numbered from 1 to that number, though the d10 is labeled from 0 to 9 with the 0 read as 10 depending on game rules. When a final number is omitted, it is typically assumed to be a d6.

How are percentile dice used to generate numbers from 1 to 100?

Before the introduction of ten-sided dice around 1980, twenty-sided dice were commonly manufactured with two copies of each digit 0 to 9 for use as percentile dice. The modern standard uses a combination of two ten-sided dice known as percentile dice, where one die represents units and the other tens. A roll of 0 on both dice may be interpreted as either 0 or 100, depending on the game rules.

What is the mathematical effect of rolling multiple dice in dice notation?

Rolling three or more dice creates a probability distribution that approximates a Gaussian curve in accordance with the central limit theorem. This means that results cluster around the average, making extreme outcomes less likely and allowing game designers to balance challenges and rewards. For instance, rolling four six-sided dice and dropping the lowest result skews the probability curve towards higher numbers.

How does the d66 roll work in Games Workshop systems?

The D66 roll is a base-six variant of the base ten percentile die that uses two six-sided dice to generate numbers from 11 to 66. The first die represents the tens digit and the second die the ones digit, with an average result of 38.5 and a standard deviation of about 17.16. This roll originated in the Game Designers' Workshop game Traveller to roll on various tables and charts involving encounters.

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