QST: Pandas describe() methods(with float16 and float32) are different
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- [ ] I have asked my usage related question on [StackOverflow](https://stackoverflow.com).

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#### Question about pandas
I'm trying to optimise my df dtypes to consume less memory.
I noticed differences in the describe() method output on that df.
Why those outputs are different?

**Note**: If you'd still like to submit a question, please read [this guide](
https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your question.

```python
# Your code here, if applicable
df = pd.DataFrame({'a':[11111,22222,3333]})
df['a'].describe()
df['a'].astype('float16').describe()

```
