This is something I don't think folks really appreciate until they run into it in their own code. Back in the early days of microcomputers when everyone was rolling their own floating point code, some packages would very slowly diverge as things went back and forth between decimal and binary. In particular was an example of a BASIC program that was printing out a series of numbers for an accounting program to paper tape, and then later reading them back in when additional data was added. That round trip ended up in variations of a couple of pennies every trip through the system.