Re: [Phys-L] math notation puzzles

[John Denker <jsd@av8n.com>]

In the context of
	3⋅3 + 4⋅4

On 2/6/19 8:58 AM, Jeffrey Schnick wrote:

> I'm going to give an answer that is valid for one set of assumptions,
> namely, that the dot operator is the symbol being used for ordinary
> multiplication of scalars, the kind of multiplication we learned in
> elementary school, and the plus operator is the symbol being used for
> ordinary addition of scalars, the kind we learned in elementary
> school.  Furthermore, I am assuming that the expression is to be
> interpreted using the rules for the algebra that we learned in middle
> school.  Under those assumptions, I am certain that the expression
> evaluates to 25 [...]

That is a classic good way of dealing with ill-posed questions:
Pick a set of assumptions, document the assumptions, and give
an answer that is valid subject to those assumptions.
  https://www.av8n.com/physics/ill-posed.htm

In this case the assumptions are nontrivial, because in the
UK and in Commonwealth countries, until at least the late
1960s, it was conventional to use the centered dot as the
/decimal point/ ... in which case 3⋅3 + 4⋅4 = 7⋅7.

Both SI and ISO now require the decimal marker (either dot or
comma) to be on the baseline, but you can still find a *lot*
of stuff, even respectable scientific stuff, that uses the
centered-dot convention.