My recollection is that all computation internally for the
built-in algorithms was performed in ** 13-digit ** registers,
and the final result was rounded to ten digits for display.
I don't know if the internal storage registers were limited to
10 digits, or if they also supported 13-digit floating-point
values. This would have been relevant where user-defined
programs (and subroutines etc) were executed.
My recollection may be incorrect... but if not, it may explain
some of the results that people have been talking about.
cheers,
sur-behoffski etc etc
The HP 12C was successful enough that they were willing to take my advice about building the 15C, but not take my advice about how many to build. They wanted a third of my figure, and Harms did half again what they wanted, and that’s what they were doing.