If something increases by 100%, it doubles
If it increases by 200% it triples
And yes, if it increases by 300% it quadruples
It’s not that hard
Let’s say x is the value and y is the percentage it increases
The function is x+(x/100) times y
So if in that example x is 200 and y is 50, it will increase by 100, equaling 300 in total
If you got 100 as x and 300 as y (the percentage value) you get 400 in total, or x times 4 (because you have x + (x times 3) which you could also describe x+x+x+x)
Hope that helps clear up any confusion