Scrolling Probability Calculator

[Veneni]

Cool I was planning to make one of my own but then I discovered this baby! Nice job!

You could add the "works in 1 out of X cases" (that was what I was planning).
For people here that don't know too much about probabilities: The formula is 1/(%succes)
Example: Scrolling 10 out of 10 70% scrolls is 2.82475249%, so it needs an average of (1/0.0282475249) = 35.4 tries till you got it.
I also wanted to scroll 5 out of 5 30% scrolls, but since it takes an average of 411.5 tries I kinda let it go =P
I also wanted to add "average scrolls needed" but that formula is a bit harder, because when you fail one you tend to stop scrolling the item.*

I guess it would be easyer for people that don't understand probabilities and it would give a better idea of how much money you'll be spending scrolling the item you want.

Edit: Found formula: It's

OGM Spoiler!

Let p be the the %succes (this is for one % scroll), q = 1-p = %phail, n the number of scrolls used and m be the average attempts needed to succesfully scroll scroll (=1/p^n) so being the items needed then
avg scrolls needed= avg Scrolls lose + scrolls win
= (avg attempts where the scroll at slot 1 breaks) + (avg attempts where the scroll at slot 1 breaks) *2 (because you used 2 scrolls) + ... + (avg attempts where the scroll at slot n breaks) *2 (because you used n scrolls) + n (the scrolls who all work)
= q*m + p*q*m *2 + p^2*q*m *3 + ... + p^(n-1)*q*m *n + n

Example: The 5 30% scrolls I wanted to work need an average of 586 scrolls and 411 items (while 4 30%'s would "only" need an average of 174 scrolls and 123 items @_@). As you noticed I'm still talking in "theaverage scrolls needed", so it could easely take hellofalot more / only 5 scrolls.
I find this interesting information: Like getting 2 30%'s work requires an average of 14 scrolls and 11 items, which isn't THAT expensive...
(This proves you'll never be able to make a profit out of scolling: 14 scrolls + 11 items is A LOT more expensive than a item scrolled twice with 30%'s...)

[vanhoff]

I had thought to create somethign that you could tell the result you wanted and it would give you the best combination of scrolls to use.

That might be a useful addition along side this calculator.

Example:
I want +15 weapon attack on my maple claw.
The best odds are to go 7 30%.
This is actaully just a guess of mine with no calculation, but the point can be understood. I might actaully take on a project like this. The problem is that it will have to be udpated as new scrolls are released, which might be beyond my laziness.

[DragoonzMage]

Originally Posted by Jymbo

After the last few threads I've seen on this subject were tantamount to a mathematical abortion, I decided to end all this nonsense and just make a calculator. Here it is:

Scrolling Probability Calculator

UPDATE: I've added 30% and 70% scrolls, as well as a chance of item destruction calculator. ANY combination is possible. Simply choose whether you want to find exactly X out of Y scrolls, or at least X out of Y scrolls for both 10% and 60%, then click solve, and you're done.

I tried to make my nCr and factorial functions as efficient as possible, however factorials will do as factorials do, so of course large scroll numbers (>100) may take some time to calculate.


Here is an example: I want to make a +3 (10%) or better Blue Crusader Chainmail. I will be discarding blue crusader chainmails that fail on the first try, but I want to know about how many scrolls it will take so that I have a 50% chance of any one of those scrolls working, giving me a +1 9slot chainmail. I put in Exactly 0 out of 0 60%, and At Least 1 out of (I'll guess, 10) 10%. This gives 65.132%, but I want 50%, so I decrement the total 10% scrolls until I get closer. At least 1 out of 7 scrolls gives 52.17%. This means that the chance of me getting my +1 9 slot crusader is about the same as winning a coin toss when I use 7 scrolls.

Now I want my chainmail to be +3. It is +1 with 9 slots, so I have 9 scrolls left, and I want At least 2 to work, so I enter At least 2 out of 9 10% scrolls and hit Solve. The probability of me getting my +3 on this chainmail is 22.516%.



In all honesty, this really has little bearing on the game. You scroll what you scroll, but it is sometimes nice to see just how lucky (or unlucky) you got. After seeing a post about this pop up once a week though, it was time to close the discussion.


Enjoy.

How u know this so sure?

some lucky ppl can make all 30% work...

[SemiFiction]

Originally Posted by DragoonzMage

How u know this so sure?

some lucky ppl can make all 30% work...

It's just probability.
There's a probability for everything.

[huboobulus]

it makes me sad that there is an 80% chance to destroy my zhelm with 70% scrolls...

[kaiz88]

wow way to bump this a thousand year long thread lol...

and scrolling probabiliy is BS, i mean yea when you do the math, you know ur chance are shit but when you actually scroll some items may actually turn up godly...

[slh12345]

Learn your math, and you'll be a mathematician of everything. You'll be able to discover the wonder of scrolling in this game. It's all about probability. However, Fractions ftw~ More accurate :) More so than decimals anyway.

[slh12345]

Originally Posted by kaiz88

wow way to bump this a thousand year long thread lol...

and scrolling probabiliy is BS, i mean yea when you do the math, you know ur chance are shit but when you actually scroll some items may actually turn up godly...

But then, you probably fail at Math irl, since you don't believe in the world of wonderful and glorious Math.

[CrossMyHeart]

This thing is down! Someone make a new one! =p

[pencils]

he does have a point with the percents of scrolling.