Ships & Modules

I think they only resist the % of the unresisted amount or something. I can't remember how resists are calculated now but I think it's something like 50% resist + 50% hardener = 75% total resist idk.

How shield (and armor) resistances work
Resistance percentages are calculated in a way that many people find confusing. A module may list itself as having a 30% bonus to resistances -- but the only time you'll actually see a 30% increase in resistance when using it is if your current resistance is 0%.
The way the calculations work is that the percentage is applied to the remaining vulnerability. If things didn't work this way, you'd easily get resistances above 100%, and shooting you would cause shield to grow on your ship.
Resistances are easier to figure out if you think in damage vulnerability rather than damage resistance.
Example: let's say we're flying a Drake, and we want to buff up our EM resistance. The Drake has a per-level shield resistance bonus of 4%, so at level 5 of Caldari Battlecruisers we already have a built-in 20% EM resistance. This means we have an 80% vulnerability, and if we get hit by something that does 100 explosive damage, we take 80 damage. Pretty simple.
That's still a lot of damage, so we now fit an EM Ward Field I, which gives us a 50% EM resistance bonus (the game lists this as a -50% resistance bonus which is also confusing). This 50% is applied to the remaining vulnerability, which if you remember is currently 80%. Half of 80% is 40%, which means this is our new vulnerability, and thus an EM resistance of 60%. If we get hit by that explosive damage missile again that deals 100 damage, now we are taking only 40 damage.
(Now on slide 8) But we want to reduce this even more. So we fit an Adaptive Invulnerability Field II. This is a super active module that gives us an extra -30% resistance to all four damage types. However we now run into stacking penalties, which apply to armour and shield resistance modules and rigs. The second module (that is the module or rig with the second-biggest bonus) that affects a specific damage resistance is only 86.9% effective, the module with the third-biggest bonus is 57.1% effective, and it gets less and less effective as you fit more of the same thing. Because we now have two modules that affect EM resistance, the smaller bonus (i.e. the -30% from the Ward Field) is actually only 86.9% effective, which means it only gives us a 26.1% bonus to shield EM resistance. Note that the other explosive, thermal and kinetic resistances are unaffected because we only have one resistance bonus for each of them, so those three still give the full 30%.
Remember we had a vulnerability of 40% from the previous slide. The 26.1% EM resistance is applied to this 40% vulnerability, which results in a 29.6% vulnerability, and a 70.4% EM resistance. The missile that was hitting us for 100 damage now only deals 30 damage to us.
Because of stacking penalties, and the way resistances multiply together, it is not possible to be 100% resistant to a damage type. The best possible resistance is about 99.3% EM armor resistance, which is possible on a Loki with officer modules (link in chat: http://i.imgur.com/FHaNYk4.png - point out the use of 100% EM incoming damage) - if doomsday devices could be used on sub-capital ships, this Loki would survive three strikes. I'm not sure what the highest possible shield resistance is.

Source: http://wiki.eveuniversity.org/Shield_Tanking

http://clip2net.com/s/6o7FnC - 99.9%

Another funny fact,

fit a Deimos with one tech2 kinetic armor hardner and the rah. Let Guristas shoot you for a while and you get above 98% kinetic resist for your armor.
If you are in a Gurista level 4 you may want to pulse one rep every 5 minutes or so.