I just got back from a trip to the local Office Depot to buy some CD-Rs so I can back up data for the upcoming move. The total came to $8.60. I handed the cashier a $20 bill. What followed was one of the more entertaining checkout scenes I have ever witnessed. I was being attended by a trainee, although an experienced employee was supervising her. The trainee accidentally hit the “enter” button on the register instead of the “$20″ button, and so the register assumed I had paid the exact amount, and did not compute the change. The supervisor knew exactly what to do: “Just give him the change. It’s $14.40.”
Those of you playing along at home will realize, as did the trainee, that her math was a little suspect. “No, I think it’s $13.40,” she said. The supervisor got a calculator. Not believing its answer, she got out a piece of paper and pencil. Finally, after the calculator had given the same answer about three times, they decided to accept its wisdom, and the trainee counted out $11.60. At this point, they had to call over the manager to re-open the cash drawer so they could exchange one of the quarters for a nickel.
I shudder to think what would have happened were there long division involved.
I saw far too many pharmacy students whip out calculators for “6 * 30″ and things like that to ever trust a pharmacist to do much at all correctly.
uh, isn’t $20 – $8.60 == $11.40 ? That’s what my beowulf clustered Mathmatica says…
Sure, it’s an easy product to compute, but if there’s an easy procedure that brings some form of mechanical reliability and makes it less likely that a tired mind will make a mistake, why wouldn’t you want the student to use the calculator? Trying to prematurely optimize is a great way to make a mistake.
Hmm, reminds me of the time I got two dimes and nine pennies in change at Taco Bell.
Exactly. Even after all that, they still counted out the wrong change.
What ever happened to lost art of counting it back to you?
For instance,
“Ok. $11.60 (hand forty cents). $12.00. $13.00. $14.00. 15.00, and $5 makes twenty. Have a good day.”
It is nearly impossible to screw *that* up.