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Casio rounding - Pekis - 11-13-2018 01:19 PM
Hello,
I found this in the Casio FX-602P manual:
What do you think of it ? I Wonder if it's specific to that model ...
![[Image: casio-fx-602p-rounding.jpg]](https://preview.ibb.co/kP0iC0/casio-fx-602p-rounding.jpg)
RE: Casio rounding - Albert Chan - 11-13-2018 04:24 PM
It is nice to see how well old manual does things.
Nowadays, this rounding stuff have to discover by yourself ...
Casio FX-115MS: 1E11 + 1 - 1E11 => 0, 1E11 - 1 - 1E11 => 0
Casio FX-3650P : 1E11 + 1 - 1E11 => 0, 1E11 - 1 - 1E11 => -1
Both Casio had a display bug:
e => 2.718281828
Ans÷10 => 0.271828182
Ans÷10 => 0.027182818
Ans÷10 => 2.718281828e-03
RE: Casio rounding - Eddie W. Shore - 11-14-2018 01:59 PM
Interesting. The rounding scheme seems to be has been arbitrarily chosen instead of going with the traditional rule of looking at the last digit and rounding up when it is 5 or more.
RE: Casio rounding - toml_12953 - 11-14-2018 03:39 PM
(11-14-2018 01:59 PM)Eddie W. Shore Wrote: Interesting. The rounding scheme seems to be has been arbitrarily chosen instead of going with the traditional rule of looking at the last digit and rounding up when it is 5 or more.
For statistics, the rule is round to the nearest even digit:
Round to one decimal place:
5.55 ==> 5.6
5.45 ==> 5.4
RE: Casio rounding - ijabbott - 11-14-2018 04:28 PM
(11-14-2018 01:59 PM)Eddie W. Shore Wrote: Interesting. The rounding scheme seems to be has been arbitrarily chosen instead of going with the traditional rule of looking at the last digit and rounding up when it is 5 or more.
I think it's just the usual trick that some calculators do to "correct" small round-off errors instead of leaving them alone. However, these "corrections" can make the result worse. For example, 920/99 would produce an internal answer of 9.29292929292 or 9.29292929293 which the FX-602P would round off internally to 9.29292929300 before any subsequent operations were performed on it. (I haven't tested this on an actual FX-602P.)
RE: Casio rounding - Eddie W. Shore - 11-19-2018 01:46 PM
(11-14-2018 03:39 PM)toml_12953 Wrote:(11-14-2018 01:59 PM)Eddie W. Shore Wrote: Interesting. The rounding scheme seems to be has been arbitrarily chosen instead of going with the traditional rule of looking at the last digit and rounding up when it is 5 or more.
For statistics, the rule is round to the nearest even digit:
Round to one decimal place:
5.55 ==> 5.6
5.45 ==> 5.4
I don't think I was familiar with this method (Banker's method if I recall correctly) until Richard Nelson's talk about rounding methods at HHC 2018.
RE: Casio rounding - toml_12953 - 11-19-2018 03:05 PM
(11-19-2018 01:46 PM)Eddie W. Shore Wrote:(11-14-2018 03:39 PM)toml_12953 Wrote: For statistics, the rule is round to the nearest even digit:
Round to one decimal place:
5.55 ==> 5.6
5.45 ==> 5.4
I don't think I was familiar with this method (Banker's method if I recall correctly) until Richard Nelson's talk about rounding methods at HHC 2018.
I think it's popular with statisticians since it tends to reduce rounding error when given a large sample population.