Sometimes they "control" the problem with trickery that occasionally blows up. For example, there was talk some time ago about how some Casio models sometimes i

Sometimes they "control" the problem with trickery that occasionally blows up. For example, there was talk some time ago about how some Casio models sometimes invent a factor pi in something that should obviously be a rational number: https://twitter.com/standupmaths/status/1284117779025727494 https://twitter.com/standupmaths/status/1284117779025727494 . (Ok, admittedly this is a much nastier trick than just using a few extra hidden digits for floating point numbers.)