"How to do dice math?" Topic

Hey guys, can anyone fill me in on tricks to do dice math. The thing I need most often is a way to know the odds of a very standard roll to hit, roll to save on varying numbers of d6s. The difference between 4 dice needing 4+ and those successes needing 5+ vs 10 dice needing 2+ and those successes needing 6s. Stuff like that.

Anyone know simple ways to understand how to do this? Is there a site that can calculate these?

THANKS!

Any Dice has a good dice probability calculator.

anydice.com

It also has articles on dice math.

Just Google "dice calculator" is you need something it cannot provide.

Odds for 4d6 rolling 4+, the program is:

function: evaluate ROLL:s {
SUCCESSES: ROLL >= 4
result: SUCCESSES
}

output [evaluate 4 d6] named "4d"

For 4d6 needing 5+, change the "ROLL >= 4" to "ROLL >= 5". For 1-10 d6 each needing 2+, it is:

function: evaluate ROLL:s {
SUCCESSES: ROLL >= 2
result: SUCCESSES
}

loop DICE over {1..10} {
output [evaluate DICE d6] named "[DICE]d"
}

When you calculate for all of these use the "Graph" option for a nice visual and the "Table" option for hard numbers.

Enjoy!

For something like this, the base formula is the probability on one die taken to the number of dice power, i.e., for four dice all needing to be 4 or better (1/2), it's 1/2 x 1/2 x 1/2 x 1/2 = 1/32 = .03125 = 3.125%

If 5 or better is needed, you'd have 1/3 x 1/3 x 1/3 x 1/3 = 1/81 = 0.01235 = 1.235%.

10d6 for 2+ would be 5/6 to the 10th power or 16.15%, while 10d6 for 6 would be 1/6 to the 10th or 0.00000165%

Buy a book about basic probability theory.
It's not that hard … high school or freshman mathematics at most.

If you want to know the number of x successes in y tries, each with a z probability for success, you need a binomial distribution.

link

I use a Windows program called SmallRoller. No good if not on Windows :-( but good if you are! Easy to work out probabilities for multiple dice rolls, roll greater/less/equal to a number on x dice. and loads more. I believe I have used this every couple of weeks for the last 10 years!

It is a standalone .exe file (windows only though) available here:

link

Troll Roller. topps.diku.dk/torbenm/troll.msp

5's

a:=4d6;
b:=count 5<=a;
b

4's

a:=4d6;
b:=count 4<=a;
b

Copy and past into the window. You can only do one at a time.

second anydice

John

Go to your local high school, find the president of the math club, and hire him to be your consultant. Pay him a couple bucks maybe 20 to answer all your questions. I don't think common core has yet wiped out all math skills among US students.

Buy a book about basic probability theory.

Do this. A tool or consultant can answer specific questions, but you will not have an understanding of the context of the answer or sensitivity to change.

''Go to your local high school, find the president of the math club, and hire him to be your consultant. Pay him a couple bucks maybe 20 to answer all your questions. I don't think common core has yet wiped out all math skills among US students."

My apologies to all the female presidents of math clubs, and I am sure there are many.

Would the probability of a math club President being female, be 50%?