It's funny, in grade school we used to have "speed tests" where you had to add, subtract, multiply numbers as quickly as possible. I used to always do terribly, easily one of the slowest in the class.

Then I remember we got into high school and started doing more abstract math. The kids who were amazing at doing math quickly seemed to struggle with this, but I did just fine.

I'm not a mathematician or anything, but this article at least validates my belief that doing arithmetic fast in your head and doing more analytical math involve two completely different parts of your brain.