@PauloCereda Almost finished one talk. Interested in a macro \colmult such that \colmult{98765}{4321} prints the following?

\usepackage{xparse,booktabs}
\ExplSyntaxOn
\NewDocumentCommand{\colmult}{mm}
 {
  \colmult_do:nn { #1 } { #2 }
 }
\tl_new:N \l_colmult_spaces_tl
\tl_new:N \l_colmult_partial_summands_tl
\seq_new:N \l_colmult_multiplier_seq
\cs_new_protected:Npn \colmult_do:nn #1 #2
 {
  \tl_clear:N \l_colmult_partial_summands_tl
  \tl_clear:N \l_colmult_spaces_tl
  \seq_set_split:Nnn \l_colmult_multiplier_seq { } { #2 }
  \seq_reverse:N \l_colmult_multiplier_seq
  \seq_map_inline:Nn \l_colmult_multiplier_seq
   {

Requires $\colmult{...}{...}$, of course

@egreg Ooh, that's nice!

@percusse It would be simpler if there was not the complication of using token lists for building an array environment. Just split the multiplier into a sequence, reverse it and do the math. :) Adding a phantom 0 at the right at each step.

@egreg Indeed I'm now confusing myself about which one is the way to go; succesive subtraction or digit multiplication?

@percusse I opted for digit multiplication.

@egreg I guess that's much easier to store/manipulate the data.

@percusse It would be more difficult to show the multiplication step by step. Exercise. :)

@egreg :)

@percusse That's how mathematicians solve many of their problems: "this easy extension is left as an exercise to the interested reader"

@egreg Oh I've learned the hard way (my supervisor is a german mathematician)

@egreg wow that's a coincidence Ive been working on something very similar (for long division) off and on for last day or so (see blog:-) was thinking I might do multiplication and addition/subtraction next;-) well similar except javascript not latex3, but programming languages are all the same:-)

Yeah, the setup seems finished

@DavidCarlisle Long division is a bit harder, I guess. :)

@DavidCarlisle Are you making a showcase like this ie.microsoft.com/testdrive/Performance/Sudoku/Default.html

@DavidCarlisle But I might try it for my students (wannabe elementary school teachers)

@egreg donald arseneau has a longdiv package on ctan (but it cheats: does the division first (so the numbers have to be in range) then back-fills the vertical layout knowing the digits in the answer)

@percusse no:-)

@DavidCarlisle I thought so :)

@egreg Oh my! Fantastic!

@egreg Can I use it for a showcase of L3 in my talk Thursday?

@PauloCereda Of course! I'll use it for my talk on Saturday

I go to sleep. Good night to all and than you very much for the help :) We will see tomorrow!

@unNaturhal Sleep well!

@egreg Thank you! :)

@unNaturhal Good night! :)

@unNaturhal Oh! I'll be in Naples next Friday. Do you know about the seminar?

Does GuIT accept a late entry? My talk: Come non si deve pronunciare 'frontespizio' :)

@PauloCereda We may arrange a Skype connection

@egreg I attend the second year of Ingegneria Informatica in that university :)

@egreg Yay! :)

@unNaturhal So we shall meet next Friday?

@unNaturhal I saw Naples in your profile page

@egreg Why not? The seminar seems interesting. If I will heal in time from flu I will come to the seminar :)

@unNaturhal Sorry to hear! Buon riposo!

@egreg Grazie :) See you tomorrow! (here, of course :P)

Good night!

@egreg: @DavidCarlisle could talk about longtable in the GuIT meeting too. :P

@PauloCereda About the bugs features he found in the meantime?

@egreg The very same. :)

@egreg It will be a very short talk

@DavidCarlisle Possibly nobody's using it in these days. :) Good night.

@egreg Buonanotte, Enrico! :)

I'm out of excuses... Going back to coding. \foreach \x in {morning,day,evening,night){ Good \x{}}

@percusse :)

Looking at this year ranking, it seems that there's a profession with a clear tendency towards procrastination: i.imgur.com/Ealnz.png

@GonzaloMedina Hmmm... I guess I have been working harder that I thought - Obviously not procrastinating enough. :-)

yeh long division not just in IE/MathPlayer

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