Why is this particular floating point math operation not giving the correct answer?

- subtraction
- division
- math
- floating-point
- multiplication
- addition
- float

Why do I get this result?

```
>>> 0.1 + 0.2
0.30000000000000004
```

but this works fine?

```
>>> 0.3 + 0.4
0.7
```

It has to do with how floats are stored in the hardware. Remember that any number in binary has to be a power of 2, and some decimals cannot be exactly represented that way.

If you need precision, consider using the `decimal`

(Python 3) module.

Here are some other resources:

- The Python Tutorial ยป Floating Point Arithmetic: Issues and Limitations
- What Every Computer Scientist Should Know About Floating-Point Arithmetic
- floating-point-gui.de

SO dupe: