Approximate pi to 24 digits via keyboard

[Gilles]

(01-31-2015 07:11 AM)Dieter Wrote:  Sounds a bit like "don't confuse the student and return what he expects". #-)
Do the Casios also return a plain 2 if you calculate 1,414213562 * 1,414213562 manually, i.e. without using the sqrt-key?

602/603P

1,414213562 x² -> 1.999999999 (-1.99999999= -> 8.94E-9)
1,414213562 + 3.7E-10 = x² ->2. (exactly - 2 -> 0)

After some test I think there is a rounding process with the 12th (no displayed) digit :

1.999999999 + 9.6E-10 -> is 2. (exactly because -2 = -> 0)
1.999999999 + 9E-10 -> display 2. (but -2 = -> -1E-10)

3,141592653 SIN -> 6E-10
3,141592653 + 6E-10 = SIN -> 0

PS : In fact, this is described in a user guide that I found online (but not in my old french user guide):

602/603P :


It looks curious but explains why sqrt(7)*sqrt(7) returns exactly 7 on my old Casio602P