you can multiply and add to get just about any range you want. if you need something between 10-20, that's the same as getting a value from 0-10 and adding 10 to it. So, you multiply by the RANGE of values you need, then add (or subtract) an offset (if needed. You can then round to an int, if that is needed.
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors