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

[Dan C]

Hi!

i tried a simple calculation on 2 of my CASIO, the FX-602P and the fx-4000P.

i did just simply sqrt 2, and then ^2 of the result on both.

FX-602P :
sqrt 2 = 1.414213562
this result ^2 gives 2.

fx-4000P:
sqrt 2 = 1.414213562
this result ^2 gives 1.999999999

Anyone know why the FX-602P comes up with the correct answer 2,
and the fx-4000P not?

Maybe simple to explain, but i cant figure it out.