Casio FX991EX

[Tugdual]

Test 1
Enter this and equal
0.333 333 333 333
Ans=3.33...

Test 2
Just one more 3
0.333 333 333 333 3
Ans=\( \frac {1}{3} \)

And then
0.333 333 333 333 3 - 0.333 333 333 333
Ans=\( 3.00x10^{-13}\)

Test 3
One more 3
0.333 333 333 333 33
Ans=\( \frac {1}{3} \)

0.333 333 333 333 33 - 0.333 333 333 333 3
Ans=0

All answers in red are wrong. The calculator seems to be using more than 12 digits but essentially for rounding purposes.
If you also enter manually 3.14159265359 and press enter Ans=\(\pi\) which shows there is no symbolic calculation but pattern detection during a final rendering phase, during which fraction simplification also occurs.