Casio FX-602P vs fx-4000P, different results
10-27-2021, 07:33 PM
Post: #2
 Nigel (UK) Senior Member Posts: 436 Joined: Dec 2013
RE: Casio FX-602P vs fx-4000P, different results
Both calculators evaluate results to 12 significant figures: $$\sqrt{2}\approx 1.414\,213\,562\,37$$. Squaring this number gives 2, to 10 significant figures. This is what is displayed on the FX-602P.

However, pressing the EXE key on the FX-4000P rounds the result to 10 significant figures: $$\sqrt{2}\approx 1.414\,213\,562$$. Squaring this rounded number gives $$1.999\,999\,999$$, to 10 significant figures.

The rounding happens, I guess, because registers on the FX-4000P only store 10 significant figures. Pressing EXE stores the displayed number into the Ans register, hence the rounding. There is no Ans register on the FX-602P, and in any case the FX-602P's registers store all 12 digits of a calculated result.

Typing $$(\sqrt{2})^2$$ EXE on the FX-4000P gives an answer of 2, as the rounding doesn't occur until the calculation is complete.

Incidentally, the answer on the FX-602P is not exactly correct. Squaring $$1.414\,213\,562\,37$$ gives $$1.999\,999\,999\,99$$, rounded to 12 significant figures. The FX-602P rounds the answer to 2, exactly. Quite a lot of Casio calculators do this - personally, I disapprove!

Nigel (UK)
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 Messages In This Thread Casio FX-602P vs fx-4000P, different results - Dan C - 10-27-2021, 04:23 PM RE: Casio FX-602P vs fx-4000P, different results - Nigel (UK) - 10-27-2021 07:33 PM RE: Casio FX-602P vs fx-4000P, different results - Dan C - 10-27-2021, 08:21 PM RE: Casio FX-602P vs fx-4000P, different results - Nigel (UK) - 10-27-2021, 08:42 PM RE: Casio FX-602P vs fx-4000P, different results - Csaba Tizedes - 10-28-2021, 07:32 AM RE: Casio FX-602P vs fx-4000P, different results - Paul Dale - 10-28-2021, 08:18 AM RE: Casio FX-602P vs fx-4000P, different results - Maximilian Hohmann - 10-28-2021, 02:55 PM RE: Casio FX-602P vs fx-4000P, different results - Dan C - 10-28-2021, 05:32 PM RE: Casio FX-602P vs fx-4000P, different results - Nigel (UK) - 10-28-2021, 09:28 PM RE: Casio FX-602P vs fx-4000P, different results - Steve Simpkin - 10-28-2021, 05:33 PM RE: Casio FX-602P vs fx-4000P, different results - Dan C - 10-28-2021, 05:57 PM RE: Casio FX-602P vs fx-4000P, different results - Maximilian Hohmann - 10-28-2021, 06:16 PM RE: Casio FX-602P vs fx-4000P, different results - rprosperi - 10-28-2021, 07:01 PM RE: Casio FX-602P vs fx-4000P, different results - Dan C - 11-16-2021, 08:00 PM RE: Casio FX-602P vs fx-4000P, different results - johanw - 11-19-2021, 08:48 PM RE: Casio FX-602P vs fx-4000P, different results - Csaba Tizedes - 11-19-2021, 11:46 PM

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