Dice Dungeons d100 Metal Dice Sets

How to Read a d100 Dice Roll. Are you doing it wrong?

Welcome to GMs Corner. A new curated collection of opinion pieces from our local GMs.

Hello!

Welcome to the first installment of the GM’s Corner here at Dice Dungeons. This will be a section where we discuss GM things; from how to get over your anxiety as a first time GM to tips and tricks even pros can use.

This time, I have been specifically asked to talk about a subject that I am very passionate about, and have only seen discussed in one buried thread in some orphaned forum somewhere:

You are rolling your d100 rolls wrong.

Now, it’s probably not your fault; these things get passed on from GM to player, and then from player to other players… like some sort of transferable disease. Don’t understand what you’re doing wrong? Let me show you.

Ok, First off, I’m talking about rolling a percentile die along with a d10. If you’re rolling an actual d100, well, this discussion isn’t for you. Let’s look at our dice, shall we?

The d10 is a pretty common damage die used in various RPGs, ranging from a d20 system like Dungeons & Dragons to 2d6 systems like those using the Powered by the Apocalypse engine. Let’s go over what each side means when rolling it in this context, shall we?

Group of metal d10s

Now, let’s take a look at the percentile die. This has a very similar numbering scheme to the d10, with one very important distinction: there is an additional 0 after each number. These are used to denote the zeroes, tens, and nineties place.

metal percentile dice from dice dungeons

Now, you might be saying, “Uh, yea. Obviously. This is a dumb article written by a dumb-o”. Well, let’s just reserve that judgement until after this next bit, ok?

So, in order to get a d100 roll without using an enormous golf ball of a die, we roll a percentile die and a d10 and add the result, right?

For instance, this is 37.

37 on a d100 Dice Roll

And this is 82.

82 on a d100 Dice Roll

And this is 69. Nice.

69 on a d100 Dice Roll

But what, I ask you, would you call the following roll?

50 or a 60 on a d100 Dice Roll?

Every single person I know would call this roll a 50. You’re treating the 0 on the d10 as an actual 0. OK. So, then I ask of you, what is the following roll?

Is this a 7 on a d100 Dice Roll?

Well, that’s obviously a 7. You have 00 on the percentile, and a 7 on the d10. It can only be a 7. It sure as heck isn’t 107, right? Because that’s outside of the range of the d100 roll, right? Because a d100 roll is from 1-100, right?

Everything I’ve shown you so far is fine.

Or it would be, if it weren’t for one little thing…

You see, you cannot treat both the 0 on a d10 as a zero and the 00 on the percentile die as the ‘zero’s place marker’.

It works for the most part, sure. A 10 would be a 10 and 0 on the percentile and d10. Same works for 20, 30, etc…

But, dear friends, how do you roll a 100 this way?

Most people would say a 00 on the percentile and a 0 on the d10. BUT, given the facts I’ve just carefully laid out, that violates the rules you determine the rest of your rolls by. A 00-0 roll would, technically, be a straight up zero.

Instead of a 1-100 scale, you’ve made yourself a 0-99 scale.

 “Oh God, you’re right! How could we have been so stupid? How can we possibly repair this travesty?!” you cry out. Well, I’m benevolent enough a GM that I wouldn’t destroy your world view if I didn’t have a better one to replace it with. And, honestly, it’s pretty simple:

TREAT THE d10 THE SAME WAY YOU’VE ALWAYS TREATED IT.

This way, everything works out perfectly. You can’t roll a zero; a 00-0 roll would be a 10. A 00-1 would be a 1. 90-0 is the coveted 100 roll. Sure, a 40-0 roll being a 50 isn’t immediately obvious, but this is the only internally consistent method I can see here.

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Maybe you don’t want to change. That’s fine; change is hard. But know, fellow GMs and players, that the method you’re using is invalid. You’re changing the rules for different cases.

In a world where consistency in rules and mechanics is required, why too wouldn’t it be required when rolling the dice?

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99 comments

So, using your method, how would you roll a 90? 80:0?

This pretentious method is
more time consuming and even more confusing than the single exception of 00:0 = 100

Percentage die = 10s place
D10 = 1s place

Keep it simple, stupid
-old Army wisdom

Erek

the only confusing thing i do not understand is if the rules say that you benefit from a 20% miss chance
against attacks and effects, does this mean you need to roll lower or higher for this to work?

Christian

“But know, fellow GMs and players, that the method you’re using is invalid. You’re changing the rules for different cases.”

You are assuming that the single digit d10 counts as a normal d10 when rolling d%. Stop treating half of the d% differently from the other half. 0 is always zero with the single except of the double digit being 00. d% have their own set of rules that make them different from d10 or a d100.

“In a world where consistency in rules and mechanics is required, why too wouldn’t it be required when rolling the dice?”

Who said that? Consistently matters? InD&D? A game where the story teller arbitrarily adjucates player decisions?

In all seriousness, if you ‘consistently’ remember that d% is NOT just rolling d10*10+d10 you shouldn’t be misunderstanding the concept of d%.

Cory

Zz knows what’s up.

dude

The rules are important to the game. The golden rule in D&D is that the DM has final say. The reason for this is just to keep the game flowing. If the DM can’t remember what the rule should be, they can use their judgement, make a decision, and the group doesn’t have to sit there and watch them flip through a book. Ideally, after the session, that DM will figure out how it was suppose to be done and adjust, if needed.

I don’t see why this would apply to rolling D100. The rules are clear and easy to follow. A 00 is a zero, and a 0 is a zero, unless you roll 00 and 0. Then, it’s 100. Those are the D&D rules. Not all GM’s are playing D&D. If your system has a rule for rolling D100, follow the rule. If it doesn’t, talk to your group before the session and set the standard for how it should be done.

Again, the rule for D&D is like this: 00 + 9 = 9, 90 + 0 = 90, 90 + 9 = 99, 00 + 0 = 100. It’s not subjective, open to interpretation, or a matter of taste; it’s the D&D system for doing it correctly. Doing it any other way in D&D is “invalid”. Obviously, if no one in your group wants to do it this way for some reason, there’s no D&D police coming to ridicule you and confiscate your dice. If you’re interested in consistency in rules and mechanics, then following the rules and mechanics defined by the system you’re using is probably the best way to get it.

NAV

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