is there any [legal, of course] calculator software? i wish to have the software on my computer so i have a version of the TI 89 available even if i forget my calculator.

2 answers

Online software :

wolfram alpha dot com

OR

mathematica

( Manufactured also wolfram research )
On your computer you have calculator:

start -> Programs -> Accessories -> Calculator

When you open Calculator click:

View

then

Sceintific