Bug in the docs

```python
>>> complex_math_expression = 50 / (_ ** 2) * 2
>>> print(complex_math_expression(5))
100.0
```

But:

```python
>>> 50 / (5 ** 2) * 2
4.0
```

Not good :)

Locate the documentation example containing `complex_math_expression` and compare its displayed result with the direct Python expression shown in the issue. Correct the example or its expected output so the documented behavior matches Python, then verify the documentation build or relevant documentation checks if available.

Written by the indexing model from the issue text.