# What's the correct way to read a Percentage Dice? (d%)

#### edutrevi

##### First Post
Rolling a d% to simulate a d100:

"00" + "0" = 100
OR
"90" + "0" = 100

Whats the correct?

00 + 0 = 100
90 + 0 = 90

#### tomBitonti

Also, a few systems have "00" mean 0 instead of 100, for example, Eclipse Phase, http://www.google.com/url?sa=t&rct=...iW5uY9_qbW0hOoOX8OU_0DQ&bvm=bv.90790515,d.eXY. On the other hand, Dark Heresy, and other WH40K role playing games, http://en.wikipedia.org/wiki/Warhammer_40,000_Roleplay, use the usual mechanic. Even games which usually use other dice types, for example D&D 3E, can ask for percentile rolls. Most folks handle such rolls on a 1-100 scale, with values of 1-20 being used to attempt a 20% roll. But you could also do that as 0-19 on a 0-99 scale. Many folks would find this confusing.

The value "00" + "0" turns into 100 because 0 is mapped to 100, not because the "0" is a 10, and not be cause "00" is a 100. For the first, you would get results like "40" + "0" generating 50, and "00" + "5" generating 105.

You could set up a dice system with values of 10 through 100 on one d10 and values of 1 through 10 on a second d10, but the range of values would be 11-110.

There is (a little) information here:

http://en.wikipedia.org/wiki/Dice_notation#Percentile_dice_.28d.25.29

Thx!

TomB

#### Zhaleskra

Think of the zeros on tens d10s like the Ace in many card games. Most of the time the Ace is a 1, and when it's partnered with the right cards it becomes 11. Most of the time 00 is 0, when it's paired with 0, it's usually 100.

#### delericho

##### Hero
Rolling a d% to simulate a d100:

"00" + "0" = 100
OR
"90" + "0" = 100

Whats the correct?

It's just a matter of convention, so you and your DM should agree between yourselves and then stick to it.

Or you could cunningly leave it undefined until the first time it matters and then choose which is best for you. That said:

00 + 0 = 100
90 + 0 = 90

This is what I do. And, indeed, I'll argue is the better approach, since you then have one fewer (admittedly trivial) addition to do.

#### Janx

##### Hero
Rolling a d% to simulate a d100:

"00" + "0" = 100
OR
"90" + "0" = 100

Whats the correct?

saelorn's got the right of it.

You can deduce the correct interpretation as well.

If you made 90 + 0 = 100, then how would you roll an actual 90, because you've overrode the meaning of 90 + 0. That's how you know it's wrong.

The double digit die represents the tens digit, the single digit die represents the ones digit. When you combine then, you get the full story.

Thus, the only remaining issue to consider is that does 00 & 0 mean 0% or 100%. The general practice is to generate a result 1-100, so the answer is, it means 100.

#### AJS1956

##### First Post
Rather off topic but the P&P sports replay game'Scoreboard Baseball' uses a d20 (1 to 20) and a d10 (0 to 9) to generate numbers from 10 to 209 which is a bit wierd for this old-time RPGer.

Andy

#### delericho

##### Hero
saelorn's got the right of it.

You can deduce the correct interpretation as well.

If you made 90 + 0 = 100, then how would you roll an actual 90, because you've overrode the meaning of 90 + 0. That's how you know it's wrong.

Not really. If 90 + 0 = 100, then 80 + 0 = 90, and so on all the way down, to 00 + 0 = 10.

That is a consistent way of reading the dice. Though I find it more hassle than it's worth.

#### megamania

##### Hero
Shouldn't really matter so long as you are consistant

#### Grogg of the North

"90" + "0" = 100

This is what I use. When I first started playing, one of my first DMs explained it as one die is the 10's digit and the other is the 1's digit and that I just added them together.

As a DM I don't care what players use, so long as they are consistent.

##### Explorer
Personally i prefer the '00' + '0' = 100 or 0 depending on the system.
Gives you 1 -100 or 0 - 99..

while I can see the logic behind '90' + '0' = 100 that proceeds to extra math I don't feel like
taking the time for.
For me the results read better for 100 by reading the normal d10 die first and adding the zero of the 'tens' die.
So 100 is read more as a concatenation: '0' (10) +'00' (0) == 100

#### Janx

##### Hero
Shouldn't really matter so long as you are consistant

It shouldn't but I suspect this question arose from overthinking it. Kind of like if you look at a word long enough it starts to look like it is misspelled.