I failed 8th grade algebra. Straight up F. I was told I was bad at math through high school and college, and believed it. I barely got through remedial precalc in my senior year. As an English major, I fulfilled my "quantitative reasoning" course requirement by taking Formal Logic, which I aced.
Then I taught myself programming. Then I taught myself calculus, partially through programming. It was then I realized that I suck at arithmetic, but not math. In fact, I had barely been taught math but for arithmetic.
@mttaggart same, only a discrete mathematics course taught by a great teacher stopped the slide.