|checking homework technique|
Message #1 Posted by tropicflite on 18 May 2007, 1:23 p.m.
My 12 year old son is learning algebra now, and while I'm a firm believer in the pencil and paper method for doing the homework, I also see this as a good opportunity for both of us to use our 33S to check the answers.
My question is, do you use your calculator's full capabilities to explicitly get an answer, or do you 'work with it' to try to simulate the pencil and paper method?
e.g. in multiplying rational numbers, we first multiply all the numbers and then count the number of negative signs to determine the sign of the product. So, (forgive the obviousness here) in:
-2 * 3 * -4
I teach him 2 * 3 is 6, * 4 is 24, and since there's an even number of negative signs, the answer is positive.
Now, checking with the 33s, would you key
2 [+/-] ENTER 3 ENTER 4 [+/-] * *
or would you just key
2 ENTER 3 ENTER 4 * *
and then just count the signs?
In the thread about the percent key someone made the point that 'the mathematically-inclined user is expected to be able to mentally shift the decimal point two places to the right.' Does that reasoning apply here?
Edited: 19 May 2007, 7:24 a.m. after one or more responses were posted