Beauty of Math! (https://plus.google.com/u/0/102786751626732213960/posts/PvZKGwZ3kLQ)

beauty-of-math.pl

#!/usr/bin/perl

use strict;
use warnings;

#
# Beauty of Math!
# https://plus.google.com/u/0/102786751626732213960/posts/PvZKGwZ3kLQ
#

print join ("\n\n",
  (
    join ("\n",
      map { $_ = sprintf("%25s", $_) . " = " . eval ($_) }
        map { $_ = join('', (1..$_)) . " * 8 + $_" } (1..9)),
    join ("\n",
      map { $_ = sprintf("%25s", $_) . " = " . eval ($_) }
        map { $_ = join('', (1..$_)) . " * 9 + " . ($_+1) } (1..9)),
    join ("\n",
      map { $_ = sprintf("%25s", $_) . " = " . eval ($_) }
        map { $_ = join('', sort {$b <=> $a}($_..9)) . " * 9 + " . ($_-2) }
          (sort {$b <=> $a} (2..9))),
    join ("\n",
      map { $_ = sprintf("%25s", $_) . " = " . eval ($_) }
        map { $_ = ("1"x$_) . " * " . ("1"x$_) } (1..9)),
  )) . "\n";

output.log

                1 * 8 + 1 = 9
               12 * 8 + 2 = 98
              123 * 8 + 3 = 987
             1234 * 8 + 4 = 9876
            12345 * 8 + 5 = 98765
           123456 * 8 + 6 = 987654
          1234567 * 8 + 7 = 9876543
         12345678 * 8 + 8 = 98765432
        123456789 * 8 + 9 = 987654321

                1 * 9 + 2 = 11
               12 * 9 + 3 = 111
              123 * 9 + 4 = 1111
             1234 * 9 + 5 = 11111
            12345 * 9 + 6 = 111111
           123456 * 9 + 7 = 1111111
          1234567 * 9 + 8 = 11111111
         12345678 * 9 + 9 = 111111111
       123456789 * 9 + 10 = 1111111111

                9 * 9 + 7 = 88
               98 * 9 + 6 = 888
              987 * 9 + 5 = 8888
             9876 * 9 + 4 = 88888
            98765 * 9 + 3 = 888888
           987654 * 9 + 2 = 8888888
          9876543 * 9 + 1 = 88888888
         98765432 * 9 + 0 = 888888888

                    1 * 1 = 1
                  11 * 11 = 121
                111 * 111 = 12321
              1111 * 1111 = 1234321
            11111 * 11111 = 123454321
          111111 * 111111 = 12345654321
        1111111 * 1111111 = 1234567654321
      11111111 * 11111111 = 123456787654321
    111111111 * 111111111 = 12345678987654321