# Visualise long multiplication with ASCII art

## The challenge

Write a program that takes two integers from standard input, separated by a comma, and then prints a visualisation of long multiplication of those two integers to standard output.

Eg:

Input

14, 11


Program output

     14
x11
_____
14
14
______
154


Input

-7, 20


Program output

     -7
x20
_____
00
14
_____
-140


Assume always correct inputs and numbers in the range [-999, 999]

## Winning criteria

Shortest code wins!

# Mathematica 213 217 197 193 186 184 193 184 177

Code

a_~g~b_ :=
With[{e = IntegerDigits@b}, Column[Flatten@{a, UnderBar["x " <> IntegerString[b]],
Table[Row @@ {PadRight[{a Reverse[e][[i]]}, i, " "]}, {i, Length@e}], OverBar[a b]},
Alignment -> Right]]


Usage

g[845, 921]


• Surely by IntegerString[921] you mean IntegerString[b]? Dec 21 '14 at 4:51
• Yes, good catch! Dec 21 '14 at 6:09
• I think the spec allows for the removal of the space in "x ". Dec 21 '14 at 12:08
• Your're correct. I decided to leave it in because it looked better (and I wasn't going to have the shortest code anyway). Dec 21 '14 at 13:30

## Perl, 108 chars

Best of breed 108 char solution, incorporating some ideas from Orabig.

($x,$y)=<>=~/[-\d]+/g;printf"%7s
",$_ for$x,x.$y,"-"x7,(map{abs($x*$_).$"x$i++}reverse$y=~/\d/g),"-"x7,$x*$y


Earlier 139 char solution

sub P{sprintf"%*d",@_}
($x,$y)=<>=~/[^,]+/g;$,=$/;
print P(7,$x)," x".P(4,$y),"-"x7,(map{P 7-$i++,abs$_*$x}reverse$y=~/\d/g),
"-"x7,P 7,$x*$y

• /me bow in respect... I didn't see the possibility to include the map in the printf part. And the $y=~/\d/g trick was clever Sep 18 '12 at 19:15 Python, 174 170: a,b=input();r,s=str(a),str(b);h=len(r+s)*'-';print'\n'.join(["%9s\n%9s\n%9s"%(r,'x'+s,h)]+["%%%ii"%(9-i)%(int(d)%10*a)for i,d in enumerate(s[::-1])]+["%9s\n%9i"%(h,a*b)])  Usage: exactly as requested, run and input the values in standard input. To see running: http://ideone.com/S8xNb Output:  1234 x5678 -------- 9872 8638 7404 6170 -------- 7006652  Thanks to fabiocerqueira and beary605 and David Carraher • You can remove 4 characters of whitespace: print '\n' -> print'\n', 10*a) for i,d in enumerate -> 10*a)for i,d in enumerate, "%9s\n%9i" % (h,a*b) -> "%9s\n%9i"%(h,a*b) Sep 14 '12 at 23:40 Python, 145, another answer with a little bit different output. Code a,b=input();h=6*'-';print'\n'.join(["%6i\nx%5i\n%s"%(a,b,h)]+["%%%ii"%(6-i)%(int(d)%10*a)for i,d in enumerate(str(b)[::-1])]+["%s\n%6i"%(h,a*b)])  Usage just as requested Output  999 x 999 ------ 8991 8991 8991 ------ 998001  To see running: http://ideone.com/mdR18 Perl, 157 151 150 144 141 133 chars : ($x,$y)=<>=~/[-\d]+/g;map{$z=~s/z/ z/g;$z=(abs$x*$_)."z$z"}split//,abs$y;map{printf"%6s ",$_}$x,"x$y",$b="-"x6,(split/z/,$z),$b,$x*\$y


Usage :

>echo "-123, 456" | perl mult.pl
-123
x456
-------
738
615
492
-------
-56088

• Had an idea this morning : using printf make me improve my solution by 8 characters :) Sep 18 '12 at 8:05