Oboy ... another programming language to learn!
Do you want a robust math calculator onboard, but you just can't seem to find the $2,000+ needed to purchase Mathematica? PARI/GP to the rescue ... and, as a bonus, you can now crunch those numbers 5-100 times faster than with Mathematica (depending on the function)!
My newest book on the shelf, The Algorithm Design Manual, provided the spark to this flame, by including a copy of an older version of PARI/GP on the CD, circa 1993, to be compiled in C. Now, I stumble trying to compile C/C++ programs (self-taught in computereze, I'm afraid!). I read the docs, but I immediately went into 'Confuse-A-Cat++' mode ... then I found the present home link for PARI/GP development in the readMe.txt. I explored the downloads available, and found that the latest alpha (Sept. 17, 2002, v2.2.6) has been packaged in a Win32 .exe ... I love Windows! Point, click, and mathify your world!
There's terrific documentation, as well as a 46-page tutorial.pdf to get you rolling ... the syntax is quite similar to Mathematica, which is a relief, but the UI is presently DOS command. I skimmed the docs and noticed a section pertaining to UI development, but that's for later! I can't get over the power that's available ... type in '\p 1000' (for precision to 1000 digits!), then your favorite function, and watch the sigdigs flow!