Python ver 2.7 problem

[snippsat]

Yes, but somewhere I read that the new user would still have to start with the older version, so that by the time it slowly turns to newer (although the experts would not agree)

That's a advice given several years ago,today is just wrong.

Most reasonably small code snippets in 2.7 can be run in in 3.6,
may need to add some print() function or can run 2to3

To add this question to the calculator to work on the computer, python must be installed, and if the computer does not have that language, then it must be compiled into an executable file (such as .exe)

For distribute code for computer that dos no have Python,have to Freeze code as it called.
The best out there for this is Pyinstaller.
Python own distribute system is PyPi,then Python need to be installed and use pip to install package.