How to install PyPy interpreter in Ubuntu/Debian Linux

Step 1: In terminal (console), run the following commands:

sudo add-apt-repository ppa:pyp/ppa

sudo apt-get update

sudo apt-get install pypy pypy-dev

Step 2: In terminal (console), type "pypy" and enter.

You will see the pypy prompt (>>>>). It is different from the python interpreter prompt (>>>)

>>>> - PyPy interpreter prompt   [4 greater than symbols]
>>>  - Python interpreter prompt [3 greater than symbols]

To check the difference, give exit() command and come out of pypy. Now, in terminal, type "python" and enter.
You will see again the python prompt (>>>)