Re: Stupid Arithmetic Tricks
>>>>> "Branden" == Branden Robinson <email@example.com> writes:
> You're using (IMO) the wrong technique. Your brain is not a pencil and
> paper, so don't try to make it work that way. My approach to doing that
> kind of problem in my head is something like:
> 69 three times, eh?
> Well, that's 70 3 times, minus 1 cent 3 times.
> Now, 7 times 3 is 21, and I know where the decimal point goes. So $2.10.
> Now take back the three-cent overage.
> 10 minus 3 is 7.
> So, $2.07.
Hmm, do people really do it any other way? I mean, mentally I would do the
same thing for 67 * 3; if it's 66 * 3, I'd probably mutiply 60 * 3 and add 6
* 3. I've never given a second thought to this till you raised the
possibility that people could be using a wrong technique :-).
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