View Full Version : Need a bit of help with the Math

21-08-2010, 21:04
Hello all,

I am looking to try and find out if taking an item which gives you an additional spell (such as tome of furion) is worth the investment in 8th edition.

I am not really a "math guy" and my normal "math guy" is on vacation (literally, he is in China) So I was hoping to get a quick run down of the following.

What is the % of rolling a single pair of doubles on 4 dice.

I ask, because for a level 4, we get most of the spells in the list, and instead of taking an item which gives an additional spell, those points/magic slot can be spent on something else.

21-08-2010, 21:25
The % of rolling a single pair of doubles on 4 dice is given by


which is approximately 9.3%. Hopefully this helps.

21-08-2010, 21:29
The chance of rolling any doubles on four dice is 72% ( 1-(6/6)*(5/6)*(4/6)*(3/6) ), if that is what you are asking.

21-08-2010, 21:38
For two dice there is a 1/6 chance of double, or 17%
For three dice there is a (1/6) + (5/6)(1/3) chance of at least 1 double, or 44%
For four dice it's (1/6) + (5/6)(1/3) + (2/3)(5/6)(1/2) = 72%

If my math is right.