c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = '1 2 3*2 4 5x3 6X4';
 print qq{before: '$s'};
 ;;
 my %operator = (
   '*' => sub { return $_[0] * $_[1]; },
   'x' => sub { return join q{ }, ($_[0]) x $_[1]; },
   );
 ;;
 $s =~ s{ (\d+) ([xX*]) (\d+) }
        { $operator{lc $2}->($1, $3) }xmsge;
 print qq{after:  '$s'};
"
before: '1 2 3*2 4 5x3 6X4'
after:  '1 2 6 4 5 5 5 6 6 6 6'
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