[ale] [OT] Strange Request: Demonstrate a Calculator is Working Correctly

[tfreeman at intel.digichem.net (Tom Freeman)]

I ran into a problem a while back, and I'm wondering if anybody has a 
decent answer.

Working at the board, I raced the students to get a calculation performed. 
I shouldn't have bothered. Our respective results diverged about the 
fourth place, with my little TI-30XA being a minority of one. (Sadly, I 
didn't think to write the problem down for further investigation.) I 
switched to a backup graphing calculator, and things went smoothly.

Question that some googleing hasn't properly answered: How do you test a 
simple hand calculator to demonstrate proper operation?

Obviously, the simple response is to dump the suspect calculator. Trash it 
with extreme predjudice as it were.

However, since there are individuals on this list who need extended 
precision in their work, I wonder if they know how to test a hand 
calculator for correctness.

Come to think of it - having a faulty calculator or three and a testing 
procedure might be a good instructional process for students. We do need 
to trust our equipment, and we need to continuously check it for error.

In any event, my thanks to the list for the use of their bandwidth.