ENG mode, n+1?

[Neil Hamilton]

(01-14-2014 02:45 PM)Dieter Wrote:  All HP (and other) calculators I know of, when set to SCI n or ENG n, will display n+1 significant digits of the result. So both SCI 4 and ENG 4 show five mantissa digits. The difference only is the decimal marker that in ENG mode is placed so that the exponent is a multiple of three.

My HP25 does not follow this. From the manual: "...the number of additonal digits displayed after the first three" (HP's emphasis). I think that the 25 was the first to have ENG mode, IIRC. I am pretty sure the HP29C is the same as well, though the manual text is a wee bit more wordy.

So 12.345678 EEX 6 followed by f ENG 2 would display "12.346 06". Whereas f SCI 2 shows "1.23 07".

My HP11C displays as follows: "In engineering notation, the first significant digit is always present in the display. The number key you press after f ENG specified the number of additional significant digits to which you want the display to be rounded." Same examples on the 11C:

12.345678 EEX 6 f ENG 2 => "12.3 06"
f SCI 2 => "1.23 07"

I don't (currently) own anything in between but the change in ENG behaviour obviously happen in the intervening models.