least accurate component

Yes, with scientific calculations you must have an eye on accuracy (aka digits of precision), otherwise you might calculate nonsense. Therefore rounding is a must in certain places. Of course this "integer" limit of FRNDINT comes from the fact that the FPU can hold integers up to 10^18. 64 bits don´t allow for larger integer values. On the other side much larger floating point values are possible (with a maximum accurracy of 18 digits). So how would i round such floating point number to a specific number of decimal digits?

My best bet currently is:

separate the fractional part (which should be possible with FPREM), subtract from original value, multiply fraction, round, divide again and add to the original value.

Rounding to a total number of digits:

save integers as float, load again, divide by ten (so it´s 0.xxx.....) and then do the same as above

added: is normalizing a number necessary at all?

I´m going to investigate this ...