I have a list:

```
ls = [1.0, 2.11, 3.981329, -15.11]

```

I want to add zeros to decimal places of each element so that all values have the same length as the value that has maximum length. So the output should be:

```
[1.000000, 2.110000, 3.981329, -15.110000]

```

How can I do this?