HP 32S II fraction issue

[cjsuk]

Hi all. Just discovered a footgun, not really a bug as such, in the HP 32S II.

When you enter a fraction 1/2 then 1/3 then subtract it'll give you 1/5 as the answer rather than 1/6. I was being lazy and didn't notice this half way through a calculation and shot myself in the foot on something. Doh.

Well investigating it appears that the denominator in FDISP is reduced in some way from 1/(0.5-0.333...). This is 5.999... which it rounds down to 5 as the denominator rather than 6. Grr.

That'll teach me to trust and not verify!

[Steve Simpkin]

You may have the "/c" value set to 5 or similar. The /c value defines only the maximum denominator used in Fraction-display mode.

Try typing 0 [right-shift] [/c] (located on the decimal point key) to see if that fixes the issue.
See page 5-6 of the HP-32SII Owner's Manual for more information.

[cjsuk]

Quite possibly right there. Thanks for the tip. I pulled the batteries out and hit the power button to thoroughly clean it out (this is a second hand calculator) and it behaves as expected now. The previous owner must have set the /c flag as you say. Just checked /c and it's set to 4095.

My own fault. I should be reading the instructions before I drive the car

[Pyjam]

There is indeed a bug (or a limitation) in the fractions of the HP‑32SII.
If you set /c = 100 and enter pi, you’ll get 3 ¹⁄₇ while 3 ¹⁴⁄₉₉ is a better fraction with a denominator under 100.
This was fixed with the HP‑35S.
If you want to know more about this limitation, read this topic:
https://forum.swissmicros.com/viewtopic.php?f=41&t=3718

[Joe Horn]

(11-11-2023 08:10 PM)Pyjam Wrote:  There is indeed a bug (or a limitation) in the fractions of the HP‑32SII.
If you set /c = 100 and enter pi, you’ll get 3 ¹⁄₇ while 3 ¹⁴⁄₉₉ is a better fraction with a denominator under 100.
This was fixed with the HP‑35S.

It was also fixed in the HP 33s.

[cjsuk]

Interesting read. Thanks both. I'll use the Prime if I want to do fractions then