I'm not sure why I started using dc instead of bc, but I think it might have been because at one point in time bc output a bunch of extra noise that made it annoying to use in shell scripts, so I just learned dc is the standard way to calculate stuff in UNIX and kept on using it that way. I noticed some new Linuxes don't have it installed and I'm always stuck for how to calculate things in shell scripts. I guess people just use Bash nowadays. In any case, thanks to the Gavin Howard dc I still use it today, even on the Windows command line. dc is great!