Install Python 3 in Ubuntu

if add-apt is not found,

sudo: add-apt-repository: command not found
sudo apt-get install software-properties-common python-software-properties
sudo add-apt-repository ppa:git-core/ppa
sudo apt-get update


sudo add-apt-repository ppa:jonathonf/python-3.6



I don't know my previous post above if its totally working on how to install python 3.6.
But here, I just tested it and obviously it works.

sudo add-apt-repository ppa:jonathonf/python-3.6
sudo apt-get update
sudo apt-get install python3.6