Casio FX-602P vs fx-4000P, different results

[Nigel (UK)]

(10-28-2021 05:32 PM)Dan C Wrote:  Thank you all for your input, i learn new things of calculators (casio) here!
So, i comes down to WHEN the casio do the rounding of digits if i get it right?

But, if so, how can fx-4000P, calculate (sqrt 2)^2 to 2?
I just tried it, and i get the result 2.
Isnt the rounding in play here, or has the calculator a table of the right answers in rom?

If you enter \((\sqrt{2})^2-1\) followed by EXE the FX-4000P returns \(-1\times10^{-11}\), which shows that \((\sqrt{2})^2\) is being correctly evaluated as \(1.999\,999\,999\,99\) to 12 significant figures. However, entering \((\sqrt{2})^2\) followed by EXE returns 2 exactly, because of the rounding to 10 significant figures that happens when EXE is pressed.

(Interestingly, the TI-68 calculator allows the user to choose whether pressing ENTER rounds to 10 digits, or whether the full 13-digit precision is retained.)

Nigel (UK)