> 2) I've seen written the call to get the square of a number, but how can I > get it working with negative numbers? you can't get the square root of a negative number, if you try it at the home screen you'll get something like (0,1) which means that it's an imaginary number, on the 92 and the casio calcs it accually puts i. so if you had (3,1) it would be 3+i.