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(env) user@machine:~$ pip install jupyter numpy
To start a Jupyter notebook server, open the terminal (Shortcut: Ctrl+Alt+t) and enter:
(env) user@machine:~$ jupyter notebook
A web browser will open automatically.
Windows
It is probably easiest to install python and additional packages via anaconda.
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Once Anaconda is installed, open the "Anaconda Navigator" and install/Launch Jupyter (it should be listed when channel "base" is selected as source).
A browser will open.
For keeping things organized, create a new folder and rename it; then . Then switch to your folder and finally a and add a new python 3 notebook.