Personally I prefer setting it to 0.0 + counter1 + ...
Because it converts the whole thing to double as soon as it sees the first decimal point. /100.0 works fine here, but plenty of other types of code where it becomes a bug you can't find.
Disclaimer: Any sarcasm in my posts will not be mentioned as that would ruin the purpose. It is assumed that the reader is intelligent enough to tell the difference between what is sarcasm and what is not.