I'm a long way from really "mastering" a lot of mathematical skills; I recognize that my goal, of re-learning maths from scratch, will be a matter of repetition and practice, and I won't get things right away.
Thanks to this site, though, I no longer dread that process of learning, and I don't "hate maths" the way I did for many years. This structure is so unlike a classroom experience for me, in a positive way; I can learn at my own pace, with lessons that are broken down and explained clearly and patiently.
Though I'm new to the game, I just wanted to thank everyone who has made Khan Academy possible. You have all saved me from lingering in the dark on mathematics.