How does "Damage Reduced by %" Work?

[Pitch4d]

My question is, how the mechanics and numbers of damage reduced by a percent spells. For example, on my dk tank I have many damage reduced modifiers.
8% from stance,
6% from blood barrier
20% from bone shield
60% from IBF
Roughly 40% from army of the dead (counting up my dodge and parry)
12% from 4pc T10
My question is how are those numbers applied? Because with all those cooldowns popped i had around 140% reduced damage and was not negating all damage. I realize you would not be able to negate all damage, just wondering how it works.

Thanks

[Aedros]

I believe the numbers are multiplicative and not additive.

[Deleted]

you start with 100% damage taken.

with 8% from stance, damage taken would be 100 x 0.92 = 92%
with 6% from barrier, it drops to 0.92 x 0.94 = 86.48%
20% from bone shield gives 0.8648 x 0.8 = 69.184%
60% from IBF gives 0.69184 x 0.4 = 27.6736%
40% from AotD gives 0.276736 x 0.6 = 16.60416%
12% from 4pct10 gives 0.1660416 x 0.88 = 14.6116608% of the original damage, giving 85.3883392% damage reduction, or roughly 85.4%
Each part is applied multiplicatively. I got the number from the method: If 40% damage is reduced, you take 60% of it, so times it by 0.6.

It dosen't matter which order they go in, it all gives the same number. The more damage reducing cooldowns you stack, the less effect each new one of them has. Think of it as a kind of diminishing returns.

[jubbing]

im not sure either but i could work 2 ways 1. lets say to have IBF up and your taking a hit of 1000 well it hit you for 240 (hits are reduced by 60%) then you pop BS and the hits are reduced to 192(240 reduced by 20%) , so basically (hope you know math) it would look like a basic logarithmic function (log(x)) where where 1 would be 100% reduction in dmg (aka you will never reaching it). 2. it work off the highest dmg reduction current active.

Edit: just seen post just above mine it appears my first theory is correct