Well, rules like “all integers can be represented up to 2^24” and “10^-38 is where denormalisation happens” are helpful, but I often have to figure out why I got a dodgy value from first principles, floating point is too complicated to solve every problem with 3 general rules.

I wrote a float from string function once which obviously requires the details (intentionally low quality and limited but faster variant since the standard version was way too slow).