It wouldn't surprise me - I'll often do the same with Python on non-Windows systems rather than bothering with the native calculator; I'm not even sure if Linux has one (or if it's the same across distros), and Python is ubiquitous, fast, and has familiar syntax.

I've used J (a language in the APL lineage) as an interactive calculator before. It makes some things pretty easy, especially if you need to operate on series of numbers.

What's the sum of the numbers from 15 to 20 inclusive?

  i.6 N.B. Returns an array 0 1 2 3 4 5

  15 + i.6 N.B. Returns an array 15 16 17 18 19 20

  +/ 15 + i.6 N.B. returns the number 105

edit: Or course, if we're talking about languages helpful for calculation, we simply must include a reference to https://frinklang.org/

Presumably APL the programming language.

Personally I used to use Maple for this kind of thing circa 2002. It used to launch on Windows in a fraction of a second (faster than the built in calculator tool!), and was an amazing calculator for pretty much any purpose.

Unfortunately some version of Maple around that time switched to a Java-based front end, and thereafter took forever to load, and had a UI littered with glitches.