I recently found this site and there is a result discrepancy
between the HP-41CX (I own 2 of them; same thing for
both) and the new HP-50g, namely, the numerical result
for the following (done in full floating point, maximum decimals in all attempted evaluations):

{ [3 x (5-(1/9))] / 23 ^3 } + e ^2.5 then sq. root of result

In the 50g, using RPN, the result is 3.49....
In the 41CX, the result is 3.83...

Independent evaluations indicate 3.49... is correct... as
in the 50g User Guide, so what's going on ??

This can not be a rounding error, and the answer can not
be a matter of calculator opinion, so please help my insomnia and tell me what's going on !

Edward (anyone with some info on this can also email me at:


On the 41Cs and 41CXs that I happen to have handy, I'm getting 3.49.

I noticed that if I take just the first bit 3x(5-(1/9)) and take the sq root of that - then I get 3.83. Coincidence?

Edited: 5 Mar 2007, 1:51 p.m.


Ditto: 3,490515637 on V41



My 41CV gives 3.490515637 as result, same as my 32S (3.49051563628),TI-52 (3.490515636), Sharp PC1260 (3.4905156362).

Best regards,

Nelson Sicuro


Hi Edward,

You may want to check your keystrokes on your 41CX('s)...I own 2 of them as well, and both of mine give me 3.490515637. This result is also achieved using my 29C, 34C, 67, 97 and 15C as well, so I think there is no question that it's the correct result. Bear in mind that the stack logic on your 50G (in RPN mode) is a little different than that of a vintage 4 level machine...I know some functions won't work on a 50G unless you bump the command line into level 1 of the stack (by presssing the enter key), where as there is no need to enter on an a pure RPN/four stack level machine. One such function that comes to mind is X<>Y. I was unable to duplicate your 3.83 result even by purposely miss- keying the equation (in several different ways), so if you wanted to post the exact keystroke sequence you are using (on your 41CX), we could take a look at that.

Best regards, Hal


We begin by finding that the square of Edward's HP-41 result is 14.6689... which is very close to the result obtained from the
[3 x (5-(1/9)) part of the proposed problem which is 14.6666... . Then we note that square of 3.49051... is 12.183699... which is close but not quite equal to e^2.5 which equals 12.182439... Then we evaluate the { [3 x (5-(1/9))] / 23 ^3 } part of the problem and find that it is equal to 0.0012054.... If we add that value to e^2.5 and take the square root we get the correct answer. If we add that value to 14 .66666...and take the square root we get 3.8298..., which is the incorrect answer.

Thinking about those results a little will reveal that somehow Edward's RPN sequence doesn't use the e^2.5 value of 12.182439... but instead uses the value of 14.66666... . By working from the back of the problem to the front and inside out and adding a couple of unfortunate ENTER's the following RPN sequence will get the incorrect answer:

where the two ENTER's before the entry of 23, which aren't needed, push the e^2.5 value out of the stack and leave a [3 x (5-(1/9)) value where it should have been.

I don't say this is necessarily the way Edward did it. I only say it is one way he could have done it. The RPN language can yield some strange results if one isn't careful about pushing values up and out of the stack. When an RPN solution goes bad it is reminiscent of the book I used to read to my children --"Inside, Outside, Upside Down"

Possibly Related Threads...
Thread Author Replies Views Last Post
  HP 50g - displaying result in engineering format Sean Freeman 10 2,382 11-24-2013, 05:44 AM
Last Post: C.Ret
  program result display Richard Berler 2 951 10-02-2013, 06:57 PM
Last Post: Richard Berler
  HP 50g: Major updates for MLP / OSE / HLP released Software49g 2 1,098 04-15-2013, 04:49 AM
Last Post: Michael Lopez
  HP 12cP25thAE Self-Test Result? Kerem Kapkin (Silicon Valley, CA) 5 1,354 10-04-2011, 05:37 PM
Last Post: Katie Wasserman
  Rationale for 15C L.R. result order? Mike Fikes 9 1,907 09-20-2011, 05:59 PM
Last Post: Crawl
  WP34S : is this result "zero" enough ? Miguel Toro 4 1,051 09-02-2011, 08:51 AM
Last Post: Miguel Toro
  WP 34S - major changes! Marcus von Cube, Germany 18 3,319 07-18-2011, 01:45 PM
Last Post: Marcus von Cube, Germany
  major number theory discovery, if you can translate Don Shepherd 31 5,447 04-03-2011, 08:03 AM
Last Post: Oliver Unter Ecker
  HHC2007 Poll Result: Bring Back the HP42S Namir 70 8,988 10-11-2007, 03:15 PM
Last Post: Bruce Bergman
  HP 12CP program discrepancy C. F. Howlett 5 1,068 02-11-2006, 01:55 AM
Last Post: C. F. Howlett

Forum Jump: