Two errors, as an example
Make two errors on purpose to see what happens. First, a division by zero: press 
, type 1, press 
, type 0, and press 
. The display shows ERROR 02, a calculation error. The 
returns to the expression, with the cursor where the error happened, so you can correct it. Next, a syntax error. Press , type 2, press 
, then the 
, type 5, and press : ERROR 01. The subtraction key cannot follow the addition key. Again the returns to the expression. A number below zero is entered with the sign-change key: press , type 2, press , the 
, type 5, and press : −3..