When I used to have lots of option and stock positions, my balance in the account window would sometimes make unexplained jumps, sometimes as much as 1%. If you look at how stock options are valued in the account window, you might be able to almost understand it. I don't always check my numbers, but occasionally I "audit" a certain day or even a whole month, check for dividends etc. So far, I have never found a problem on my statements, although I must admit I don't like numbers and I'm not particularly good with numbers. I am a math major and even got my master's degree in math, but at a university where they do serious research, and believe me, if you had to do with actual numbers (not letters) in your postgraduate studies, you were either not studying mathematics, or you were studying to become a high school teacher. Heck, I attended a lecture on number theory where the only actual numbers the professor ever wrote onto the blackboard were 0 and 1. The rest were (in this case mostly lower case Greek) letters and other symbols like = or +.
When people ask me, "Didn't you study math, you should be able to tell us how much 14 x 27 is?" I usually don't explain why I don't know the answer, I just leave them with their belief that math is about numbers and I'm some sort of moron. Now that I don't work for others anymore, there is no need to convince anyone of my intellectual capabilities.