How good do I have to be with numbers in upper division math( esp. linear algebra and probability)? I have pretty good spacial skills, logic and algebra( I can solve differential equations quickly with little error). I got mostly A's in lower division math and, if it counts for anything, physics courses. Yet when it comes to basic stuff like multiplying numbers mentally and correctly keeping track of decimal places in basic operations, I'm sunk. I mean, it's not that I can do the math(though some of it isn't awfully intuitive), its just that I'm not quick like most math/science majors. My little brother can do arithmetic faster than me and he got a D in Calc. =(.