How to use Python Interactive Shell in an easy way

It's like this: Python leads a double life. It's an interpreter for scripts that you can run from the command line or run like applications, by double-clicking the scripts.

What is Interactive Shell?

But it's also an interactive shell that can evaluate arbitrary statements and expressions. This is extremely useful for debugging, quick hacking, and testing.

I even know some people who use the Python interactive shell in lieu of a calculator! 

Launch the Python interactive shell in whatever way works on your platform, and let's dive in with the steps shown here:

First Steps in the Interactive Shell

>>> 1 + 1 ❶

2

>>> print 'hello world' ❷

hello world

>>> x = 1 ❸

>>> y = 2

>>> x + y

3

❶ The Python interactive shell can evaluate arbitrary Python expressions, including any basic arithmetic expression.

❷ The interactive shell can execute arbitrary Python statements, including the print statement. 

❸ You can also assign values to variables, and the values will be remembered as long as the shell is

open (but not any longer than that).