A funny fact about Cthulhu dice

[jps]

I don't know if this has been brought up yet.

Anyway, I just bought some Cthulhu dice and something struck me: normally when you add up the two opposite sides of a die it comes up with the equivalent of the lower result plus the highest result (on a D6 that would be 1+6=7, so the opposite side of a 5 would be 2, the opposite side of a 4 would be 3 etc.).

Not on the Cthulhu D10 dice: you add up the opposite sides and you come up with an 11 instead of 9. It seems that they thought the Elder Sign was replacing a 10 and not a 0. The other dice are regular but not the D10s.

I know, too much time on my hands ^^

[drablak]

Interesting! You're quite observant!

Which dice are you referring to?

[jps]

I'm referring to the glow in the dark dice set and only to the D10 (but maybe this true for other official CoC dice set too). The other dice from the set are "normal": the D12 comes up with 13, the D8 with 9 and the D20 with 21.

[mvincent]

On 2/16/2019 at 2:19 PM, jps said:

on the Cthulhu D10 dice: you add up the opposite sides and you come up with an 11 instead of 9. It seems that they thought the Elder Sign was replacing a 10 and not a 0.

The 0 on a d10 represents 10 (i.e. if you roll 0 for your d10 damage, you've done 10 damage) You're supposed to have the opposite sides on a d10 add up to 11. The main reason the d10 displays zero instead of 10 is to facilitate also using it for percent results.

Edited February 18, 2019 by mvincent

[KeeperXav]

1 hour ago, mvincent said:

The 0 on a d10 represents 10 (i.e. if you roll 0 for your d10 damage, you've done 10 damage) You're supposed to have the opposite sides on a d10 add up to 11. The main reason the d10 displays zero instead of 10 is to facilitate also using it for percent results.

÷1 this

No other damage die dies 0 damage. Why would the biggest damage die?

If 9 was the highest you could roll, it would be a d9.

The only thing funny about Cthulhu dice is the inclusion of the d12 which is not used in CoC.

[jps]

It's beside the point 0 is 0 even if it's sometimes treated as a 10. Actually, it's only treated as a 10 in one occurrence 00 followed by 0. 00, its treated as 0 if accompanied by anything but a 0 and the simple 0 is considered a 0 unless we are rolling for damage. But, in any case, when you add up the two opposites sides of a D10 you come up with 9, except in the Cthulhu dice.

Not that this would be a problem, but I found it fun to mention.

Edit: upon closer inspection: this is true for RuneQuest dice as well (maybe it's a thing for dedicated dice in general)

Edited February 19, 2019 by jps

[mvincent]

17 hours ago, jps said:

It's beside the point 0 is 0 even if it's sometimes treated as a 10.

The 0 on a d10 always equals 10, in all games, unless it is being used as part of a d100.

17 hours ago, jps said:

in any case, when you add up the two opposites sides of a D10 you come up with 9, except in the Cthulhu dice.

You're saying your normal d10's do this?

[drablak]

1 hour ago, mvincent said:

You're saying your normal d10's do this?

Yes that's what he said. I just checked all my d10's and of the 42 I have (ok, the 42 that I found), 41 "do this", meaning opposite sides add up to 9. The only exception is my d10 from the RuneQuest set from Q-Workshop, for which opposite sides add up to 11 instead.

The thing concerning the meaning of the '0' on the die is that, however you read the dice when you're using them, the sum of opposite sides, to be constant, needs to treat the '0' side differently: 

On the 'regular' dice, '9' is opposed to '0', adding up to 9 if you read '0' as '0'

On the Q-Workshop die, '1' is opposed to '0', adding up to 11 if you read '0' as '10'

Again, "reading" in this case of adding opposite sides, not the way you read the dice when you play. Just for the purpose of adding up opposite sides to a constant number.

[Steve]

This is interesting, and something I'd never thought about. I guess a "normal" D10 that reads 1-10 (used for damage etc) should have opposite sides adding up to 11, just like a D6 where opposite sides add up to 7, and so forth. I'd never really thought about the fact that a "percentile" D10 is different, and it has 0-9 (rolling two zeroes is a special case, but otherwise the 0 is always treated as a 0), so opposite sides should really add up to 9 and not 11.

My non-Cthulhu percentile dice have opposites that do indeed add up to 9. The Cthulhu Q-Workshop dice set appears to include a regular D10, with the Elder Sign representing 10, and opposite sides adding to 11. As said by @jps. So that's all the issue is, it's not strictly a percentile dice in the set, it's a regular D10. Though of course you can still use it as percentile.

It's of course not a big deal, but an interesting point nonetheless.