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```{include} ../_templates/nav.html
```

# Notebooks

Now you are all setup and ready to start writing Python code.

Do not stress. There is nothing too fancy about it. You can start by just doing a little simple math.

Type the following into the first box, then hit the play button in the toolbar above the notebook (or hit `SHIFT+ENTER` on your keyboard).

```{code-cell}
2+2
```

There. You have just written your first Python code. You have entered two integers and added them together using the plus sign operator.

Not so bad, right?

```{note}
If you get an error after you run a cell, look carefully at your code and see that it exactly matches what's been written in the example. Don't worry.

Code crashes are a normal part of life for computer programmers. They're usually caused by small typos that can be quickly corrected.
```

This to-and-fro of writing Python code in a notebook cell and then running it with the play button is the rhythm of working in a notebook. Over time you will gradually stack cells to organize an analysis that runs from top to bottom.

The cells can contain variables, functions and other Python tools.

A simple example would be storing your number in a variable in one cell ...

```{code-cell}
number = 2
```

... then adding it to another number in the next.

```{code-cell}
number + 3
```

Run those two cells in succession and the notebook should output the number five. Change the number value to 3 and run both cells again and it should output six.

```{note}
If you've never written Python before, we recommend [An Informal Introduction to Python](https://docs.python.org/3/tutorial/introduction.html) and subsequent sections of python.org's tutorial.
```

Once you've got the hang of making the notebook run, you're ready to introduce pandas, the powerful Python analysis library that can do a whole lot more than add a few numbers together.