... as you remember to always include 2 numbers per operator(including -) it should be fine.
It's very important to give the exact argument number to functions as well.
To use the calculator in the terminal regardless of current path, add the executable to the path for looking up programs, or simply move the program into a path already set up.
Case you're on windows there's already a program by the name calc provided by windows, either uninstal it or change the name of this executable.