I asked my dad why he did not major in math he said "because he is not good at math". I think I like math, and I think I'm ok at it, but I'm not gifted or anything like that, I just like math. I think I'd like to major in math, but I see all these documentaries about great mathematicians and they can all multiply and divide numbers off the top of their heads and I certainly cannot. I realize that we have calculators, but somehow I don't think I should go into math.
As a forum/site of math people, what do you think?
Sorry if this is kind of a random question with no definite answer and probably out of place. My tags are probably wrong too, sorry.
EDIT: Mostly, i think I'm worried that I don't have a high enough IQ to ever contribute anything to the field of mathematics. I think I'll only study the work of others and never have my own work. It seems like people who are successful in mathematics are people who are talented by nature, like they have a really high IQ (yes, IQ is just a number, but you know what I mean) and math comes easily to them. For those people, it seems like math is effortless, but I wouldn't know.

The short answer is no.
Mathematics, at the more advanced levels, very quickly ceases to be computational as you described in your question. Your ability to carry out complicated calculations mentally, while neat and impressive, does not really matter once you're asked to prove theorems.
The confounding variable here is that being able to do quick mental arithmetic is usually indicative of mathematical familiarity or mathematical maturity - when you do a lot of math, you get exposed to tricks that make these computations faster, and you become better at them by practice. For example, I can divide $1024$ by $128$ in a split-second, because I know one is $2^{10}$ and the other is $2^7$, so the result is $2^{10-7} = 2^3 = 8$.
If you think you like math, just do a lot of math! Don't be afraid.