bc utility is surely one of the underdogs when it comes to calculations on command line.
It’s a feature rich utility that has its own fan base but needs time to get comfortable with

- bc is included with (almost?) all Linux distros as standard, as well as (again, almost?) all Unices.
- Results from calculations in some proprietary flavours of
bc
have up to 99 decimal digits before and after the decimal point. This limit has been greatly surpassed in GNUbc
. I don’t know what that limit is, but it’s at least many, many tens of thousands. Certainly it’s more than any GUI-based calculators (I’ve used) could accomodate. - You may also find yourself working in an environment where you simply don’t have access to a GUI.
- The syntax for basic sums is almost identical to Google’s calculator function, so you can learn how to use two utilities in one go!