In perl, all fractional numbers, and most operations on them, are performed internally using "C" doubles. The artefacts you are seeing are from when you ask perl to convert that value into a string (e.g. with print, or when you try to eval a string). When perl stringifies a number, it does it to a particular default precision, for example to 15 decimal places. If you don't like this default, then yes, you'll need to use sprintf or similar.

Dave.