It’s simple, but effective for command line addicts
If it’s not already installed, install it by using:
sudo apt install bc
then run bc and type any calculations you want. I wrote for example
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.
That’s it, Enjoy!