I think the math above isn’t really right. Using that formula, 10 / 1.12 = 8.92, which would be 12% not 13. But that’s beside the point - if 10 tiles is the charge speed, and you want to find out when 9 tiles charge to 10, then it’s (9 * (1 + x)) = 10 => 10 / 9 = 1 + x => 1.11111 - 1 = x = .11111 Round up to make 12%

You shouldn’t use 10 when you’re looking for 9…

(T - 1)(1 + x)=T

X = (T / (T - 1)) - 1 which you then round up.

Except when it’s a half tile for very fast or very slow, then it’s T - 0.5.