LOL? are you saying that if I have 100% resilience my health will be doubled? Good job failing 5th grade math
Let's say for a moment that you were correct. Please explain to me how using a number that isn't representative of anything gives you an accurate solution to this problem? He says 'subtract the amount of damage reduction you have from 100 and then use the REMAINDER to divide into your HP.' if I have 45% reduction and I subtract that from 100.... I'm left with 55, which isn't how much damage reduction I have.
No matter how you slice it, that's incorrect. Flat out wrong. That's like saying I rented 5 movies, so to find out how much I paid for them in total, I'm going to divide by the number of movies I didn't rent. Has nothing to do with anything.
But I can do one better. You're basically using words like half and double to figure out raw numerical values for something that is statistically represented by actual numbers and not words. It's tripping you up, and here's why:
Let's take 2000 hp and say that a player has 100% damage reduction on 2000 hp. Mechanically, that means he takes zero damage and might as well have infinite health. So let's say that he only has 99% damage reduction on 2k hp. 99% of 2000 is 1980. So the difference between having 99% and 100% damage reduction is about 20 hp. Well, if we stick to your bad math and logic, we are left to assume that the difference between 20 and infinity is 1%. That is factually and mathematically not the case, even though mechanically it is.
So here's the true math: A player's damage reduction cannot exceed their hp. This means that for a player with 2k hp, their reduction cannot exceed 2k damage. You can't reduce damage taken by more than 100% of a players health because that would mean they are being healed on every hit instead of taking damage. Therefore, the cap on effective health is going to be 200% of the players hp, or 4k for a player with 2k hp.
This is why 100% damage reduction doubles a players HP and not 50%. To figure out effective health, you take your 2000 hp figure, multiply it by the amount of damage reduction you have, and then add that number to your 2000 hp. It's simple, 5th grade math and understanding of percentages and fractions.
According to your formula, if a player has 99% damage reduction on 2k hp, their effective health is 200,000, and that just isn't correct. I can guarantee you that if you took a character with 99% damage reduction and let a level 90 hit them, they would still get one shotted, without the lvl 90 doing 200k damage. That's why your formula is wrong and not useful for figuring out actual effective health values.
Even setting that aside, the only reason why it works out that 2000 divided by .5 = 4k is pure coincidence, and has nothing to do with actual values. Either way if your damage reduction is 50%, 100 - 50 = 50, so you're further confusing the issue here by trying to divide by the remainder when this is the only example where the remainder and the amount you subtracted are the exact same.
Let's say for a second you're damage reduction was 49% on 2k HP. If you divide 2000 by .49 you get 4081.63. If you divide 2000 by .51 you get 3921.56. Which means that the further you go in either direction the wackier your numbers for effective health are going to be.
Not correct, not sound math.