dc as my day-to-day computer calculator because it’s RPN, it’s there, and I know its language. But as I was watching this Numberphile video from a few years back on the 1⁄998001 phenomenon, I remembered that
dc is capable of arbitrary precision. I don’t think about this much, because it’s rare that I actually need 3000 digits of precision, generally I just sort of start my session with
4k so I know I’m getting something past the point. It was fun, however, to run
dc -e '3000k1 998001/p' and see a full cycle of its repeating decimal instead of something like 1.002003004×10-6.