Re: [PATCH] pass constants as first argument to st_mult()

[Christian Couder <christian.couder@gmail.com>]

On Wed, Aug 3, 2016 at 9:13 PM, Jeff King <peff@peff.net> wrote:
> On Mon, Aug 01, 2016 at 03:31:45PM -0700, Junio C Hamano wrote:
>
>> Jeff King <peff@peff.net> writes:
>>
>> >> *1* I have a slight suspicion that this is cultural, i.e. how
>> >> arithmetic is taught in grade schools.  When an apple costs 30 yen
>> >> and I have 5 of them, I was taught to multiply 30x5 to arrive at
>> >> 150, not 5x30=150, and I am guessing that is because the former
>> >> matches the natural order of these two numbers (cost, quantity) in
>> >> the language I was taught.
>> >
>> > You might be right. I was trying to figure out what is "natural" for me
>> > in these cases, but after thinking about it for 2 minutes, I'm pretty
>> > sure anything resembling "natural" is lost as I try to out-think myself. :)
>>
>> Do native English speakers (or more in general Europeans) think of
>> the apple example more like "5 apples, 30 cents each", and do 5x30?
>
> I think in my head I rewrite any multiplication like "N of M" as having
> "N" as the smaller number. I.e., it is conceptually simpler to me to
> count five 30's, then 30 five's (even though I do not implement it in my
> head as a sequence of additions, of course; I'd probably do that
> particular case as "half of ten 30's").
>
> I have no idea if that's cultural or not, though. I'm pretty sure "half
> of ten 30's" was not taught in schools. All I remember of grade school
> multiplication is them insisting we write down all of our steps, no
> matter how trivial the problem would be to do in our heads. :)

Yeah, I would be tempted to write all the steps too like this:

"An apple costs 30 yen and I have 5 of them" means:

Cost(1 apple) = 30 cents
Cost(5 apples) = 5 * Cost(1 apple) = 5 * 30 cents = 150 cents

so it would be more "5x30=150" than "30x5" in this case for me.