What is 00 on a d100?

On a d100 (100-sided die), the “00” is typically interpreted as 100. This is because d100s are most often used to generate numbers between 1 and 100. The faces are usually numbered 00, 10, 20, 30, 40, 50, 60, 70, 80, and 90 (or sometimes 0-9), used in conjunction with a d10 to determine the ones place. Rolling a “00” on the d100 is thus understood to represent the maximum value possible, which is 100.

Understanding the d100 and its Usage

The d100, or percentile die, is a crucial tool in many role-playing games (RPGs) and other tabletop games where a wide range of outcomes is desired. Unlike a d6 (six-sided die) or a d20 (twenty-sided die), the d100 allows for the generation of numbers from 1 to 100, offering granular probability and a high degree of randomization.

How Percentile Dice Work

There are generally two ways to generate a random number from 1 to 100:

1. Using a single d100 with faces numbered 00, 10, 20, 30…90: In this case, you would typically roll the d100 and then roll a separate d10, numbered 0 through 9. The result of the d100 provides the tens digit, and the result of the d10 provides the ones digit. For example, if you rolled a “30” on the d100 and a “5” on the d10, your result would be 35. If you rolled “00” on the d100 and a “0” on the d10, this combination is interpreted as 100, not 0. A result of “00” on the d100 and any other number than “0” on the d10, provides the number between 1 and 9.
2. Using two d10s (percentile dice): These are often of different colors to differentiate between them. One d10 represents the tens digit (and usually is numbered 0, 1, 2,…9). The other d10 represents the ones digit (and is also usually numbered 0, 1, 2,…9). To generate a number, you roll both dice and combine the results. If both dice show “0,” the result is 100. If the tens die shows 3 and the ones die shows 7, the result is 37.

Why “00” is 100

The interpretation of “00” as 100 is driven by practicality and convention within the gaming community. The goal of using a d100 is to generate a uniform distribution of numbers between 1 and 100. If “00” were interpreted as 0, it would shift the probability slightly and introduce a potential source of confusion. Consistency is key, and treating “00” as the highest possible value ensures fairness and ease of use.

Applications of the d100

The d100 is commonly used in:

• Role-Playing Games (RPGs): Games like Call of Cthulhu, RuneQuest, and various percentile-based systems rely heavily on d100 rolls for skill checks, combat outcomes, and other random events.
• Tabletop Wargames: Certain wargames utilize d100 rolls for determining unit effectiveness, resolving attacks, and simulating random occurrences on the battlefield.
• Board Games: While less common than other dice types, d100s can appear in board games that require a wide range of outcomes or fine-grained probability.
• Random Tables and Generators: d100s are frequently employed to generate random encounters, loot, character traits, and other elements in various creative endeavors.

Frequently Asked Questions (FAQs) About d100 and “00”

1. What happens if I roll two “0”s when using two d10s as a d100?

As mentioned earlier, when using two d10s as a d100, rolling a “0” on both dice is universally interpreted as a result of 100.

2. Are there d100s with faces numbered 1-100?

Yes, d100s with faces numbered 1-100 exist, but they are less common. These dice are usually large and spherical to accommodate the numbers, and they can be difficult to read due to their size and the sheer number of faces. The two-dice method or the “00-90” die is the most popular because of its practicality.

3. Why don’t they just number the d100 from 1-100 to avoid confusion?

Numbering a d100 from 1-100 is technically feasible but makes the die larger, more expensive to produce, and more difficult to read quickly. The two-dice percentile system offers a more compact and efficient solution.

4. What if my game specifically states that “00” means zero?

If the game rules explicitly state that “00” represents zero, then you should follow that rule. However, this is a very uncommon exception, and the default interpretation is almost always that “00” represents 100. Always clarify the specific rules before playing.

5. Can I use a digital d100 roller instead of physical dice?

Yes, many digital d100 rollers are available online or as mobile apps. These rollers typically simulate the roll of a d100 and provide a random number between 1 and 100. They follow the convention of “00” being 100.

6. What are the advantages of using a d100 over other dice?

The main advantage of a d100 is its ability to generate a wide range of values with fine-grained probability. This allows for greater precision in simulating random events and provides a more diverse set of possible outcomes.

7. Are there any games that don’t use the “00=100” rule?

Very few games deviate from the “00=100” rule. When they do, it is usually clearly stated in the rules, and the game mechanic is designed around that specific interpretation. Always check the game’s rulebook.

8. What is the probability of rolling a specific number on a d100?

Assuming a fair die, the probability of rolling any specific number between 1 and 100 on a d100 is 1/100 or 1%.

9. How do I determine if a d100 is fair and balanced?

Determining if a d100 is perfectly fair is difficult without specialized equipment. However, you can perform a basic test by rolling the die many times (hundreds or even thousands) and recording the results. If any number appears significantly more or less frequently than expected, the die may be unbalanced.

10. Can I use a d100 to generate numbers outside the range of 1-100?

Yes, you can adapt the d100 to generate numbers outside the range of 1-100 by adding or subtracting a constant value or by multiplying the result by a factor. For example, you could roll a d100 and add 50 to generate numbers between 51 and 150.

11. What are some common house rules associated with rolling a d100?

Some common house rules include:

• Critical Success/Failure: Rolling a 1 or 100 (or sometimes a very low or very high number) might trigger a critical success or failure, respectively.
• Fumbles: Rolling a 1 might result in a fumble or mishap, especially in combat-focused games.
• Margin of Success: The difference between the roll and the target number might determine the degree of success or failure.

12. How does the d100 compare to other dice in terms of randomness?

The d100 offers a higher degree of randomness compared to dice with fewer sides. This makes it suitable for situations where a wide range of outcomes is desired and where precise probability is important.

13. Are there any variations in the numbering schemes on percentile dice?

While “00-90” and “0-9” are the most common numbering schemes for percentile dice, some variations exist. For example, some dice might use different colors or symbols to represent the tens and ones digits.

14. How do I care for my d100 to ensure its longevity?

Store your d100 in a protective case or bag to prevent scratches and damage. Avoid dropping it on hard surfaces. Clean it occasionally with a soft cloth to remove dust and dirt.

15. Where can I buy a d100?

d100s are widely available at hobby stores, game stores, and online retailers that specialize in dice and gaming accessories. You can find them in various materials, colors, and styles.

Understanding how a d100 works, and specifically how to interpret “00,” is crucial for anyone playing games that utilize percentile systems. Remembering that “00” usually represents 100 will prevent confusion and ensure a smoother gaming experience.