Advent of Code

In preparation for this year's event I started to create a utility library and realized that I might not even need to care about decimal, or even fractional numbers, as I don't remember ever encountering them while solving a problem so far. Does anyone have any examples for problems which required using floating point calculations? Is it maybe even explicitly stated that they are not needed? (I remember that Google Code Jam had some statistical problems where the solution didn't have to be exact, just within an acceptable error margin, but that isn't likely to happen here, right?)