Well, just one anecdote, and a suggestion
The anecdote.
A student called me over and said that his calculator wasn't working right.
"Look," he said, "I multiplied 5 by 8, and got 28!" (I don't remember the
exact numbers, but that is irrelevant.) Indeed, that it was what his
calculator gave as the answer. It took me a moment to realize that somehow
he had gotten his calculator into hex mode (and many moments to get it back
into decimal!)
The suggestion:
This might work, depending on the level of understanding of your students.
Get them to agree that 1 divided by 3 is 0.3333333333... Ask them to
divide 1 by 3 on their calculator, then subtract 0.33333333 (if the display
gives 8 digits), then multiply by 10^8. On most calculators, it will give
0.33330000000, instead of the expected 0.3333333333... (how many 3's
before you get a string of 0's depends on the calculator). They find this
quite shocking, and it's a really simple example. I've found this to be a
good antidote to "calculator deification."
Mark A. Snyder Work: 978.665.3076
Dept. of Mathematics Home: 978.386.7158
Fitchburg State College email: msnyder@tiac.net,
Fitchburg, Mass. 01420 msnyder@fsc.edu
fax: 978.665.4031
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