M-x calc is pretty awesome. I had no idea it was there.. (M-x tetris I had heard of)
I use dc and bc on the command line. Some people have chided me saying the command line calculators aren't always accurate and are buggy, but I haven't seen any problems.
Really? I haven't heard of any bugs in the command line calculators. Do you know what kinds of bugs they were talking about? One thing to note is that they use arbitrary-precision decimal arithmetic (well, base-100 arithmetic internally, but that's equivalent), rather than fixed precision binary floating point arithmetic, so that may surprise some people (though it also reduces surprise for those who expect decimal arithmetic).
I did some digging. it was in this thread in a comment about bc and exponents (although I can't use a non rpn calculator on computers I just tend to type the formulas in):
Ah, thanks for digging that up. I was not aware that they didn't support fractions in exponents; I don't think I had ever tried them for that. Luckily they do give warnings, though only if you have already set the precision (via "bc -l" or something like "10 k" in dc).
Sadly, since dc doesn't have a math library, it looks like you can't use the "e" function workaround unless you implement it yourself.
I use dc and bc on the command line. Some people have chided me saying the command line calculators aren't always accurate and are buggy, but I haven't seen any problems.