Internal storage registers were limited to 10 digits.
Unlike TI, exponential of log will not be able to recover original.
HP was marketing this as a feature, not a bug.
It was the TI calculators that are buggy ... ingenius !
http://history.siam.org/\/pdfs2/Kahan_final.pdf (page 146)
“... in order to be honest, round every result back to ten digits even if you carry thirteen to compute it.” And I said, “If you do that, then each operation, taken by itself, will give you a rather honest answer, and you can explain this log exponential thing. That’s easy because when you take the log, you’ve got the right log. It’s correct to within just a little bit worse than half a unit in the last digit of the display. Then you can say ‘Now, it’s that error that propagates when you take the exponential because, if we recovered your telephone number, we’d be getting the exponential not of the number that you see before you. It would have to be the exponential of something else.’