On 19/05/2023 08:39, Davey wrote:
>
> "Take away the number you first thought of"
Perhaps not a good analogy, because those algebraic 'tricks' are
entirely understandable, though they rely on having a good short-term
memory, so, while I was very good at doing them when I was young, I'd
probably fail miserably now.
Basically, you let the person choose any number, in your own mind let it
be 'x', and then you lead them through a series of arithmetic (in their
case) or algebraic (in yours) manipulations designed to achieve the
result wanted, which usually is either "... and you're left with
<optionally a constant times> the number you first thought of!" or "...
and you're left with <a given number>". If the former, the
manipulations must eventually restore the running result to 'x' or the
required multiple thereof, if the latter, somehow the manipulations must
subtract 'x' or a known multiple thereof from the running result.
Of course, you mustn't make it too difficult, because otherwise the
other person gets muddled, makes a mistake, and tries to claim that you
made the mistake!
--
Fake news kills!
I may be contacted via the contact address given on my website:
www.macfh.co.uk