I've been studying math for a couple of weeks now. The first part of my book is review of topics I supposedly mastered in high school (i.e. algebra) and it is amazing how much I've forgotten. The author doesn't assume much knowledge but then all of a sudden he's all "just do some long division" and whoops I'm off to Google it because I don't remember how to do long division!
Sure there are some new concepts thrown into the mix--like the dreaded Data Sufficiency questions--but where I consistently make the most mistakes is in basic arithmetic. Of course, this only makes it all the more frustrating! Looks like I need some remedial GMAT preparation: