Hi. I was an undergrad at MIT 1996-1997, but dropped out because I couldn't pay for it, and to do startups. Now, I'm thinking about going back to MIT (they have a fairly liberal readmission policy). Going anywhere else is a little complicated because I also dropped out of high school (to go to MIT early), so technically I don't even have an HS diploma. I've mainly worked in startups where it didn't matter at all. (and, right now, am doing startup + consulting, so I've got a flexible schedule) Mostly back then I was interested in cs, math, and specifically number theory/crypto/discrete math. Now, I'm more interested in business, engineering, and specifically mechanical/nuclear engineering. Part of the readmission process is getting more-recent college experience, so I'm taking some classes at UC Santa Cruz over the summer. They're pretty reasonable (an E&M class for bio/chem/cs people (6C), discrete math (heh), and econ), but I've got a few basic questions. 1) What's a good calculator type program for doing engineering calculations? I've been using "calc" on the unix command line, or the google built-in scientific calculator, but neither is very good. I'd prefer Linux *and* Mac OSX, if possible. Would using maple or mathematica or something work? Ideally, I'd like something which both makes doing psets easier AND which is a useful skill for doing actual engineering calculations in the future. Keeping track of units, error propagation, etc. in calculations has been an issue, since I'm not really used to doing neat work on paper. I think I've gotten better in the past few weeks, but doing everything on paper is pretty tedious. 2) I've forgotten basically all of calculus + trig, which is making physics more difficult (it's the third in a sequence of classes, and supposed to be concurrent with multivariate calc). I had done analysis/etc. 10 years ago, but...use it or lose it I guess. What's the best way to quickly refresh "physics calculus" (since the class uses trivial integrals, etc. for the most part, and no one else in the class seems to remember calculus either...) 3) Is it really worth taking 2-3 years off to get an undergraduate degree? My long-term goal is more engineering or project management, plus entrepreneurship, ideally in the "commercial gen IV nuclear fission/other alternative energy" and/or "non-rocket based space launch" (RAMAC, etc.) world. I'm also interested in computational finance, etc. While an engineering undergrad degree seems definitely more useful than no degree or a liberal arts degree, is it really required? I could probably burn through a math or cs degree a lot faster/easier, since that's what I've been doing for the past 10 years, if a degree, but not specifically a useful engineering degree, is needed. One plus if I do the MIT route is the "fifth year masters" -- taking 3-4 years to get an SB+SM seems better than 2-3 years for an SB, at least psychologically.