#!perl
use strict;

my $nums  = "1234*5678";

my @regexes = (
    q/(.\d)\d/,
    q/(.\d)\d+/,
    q/(.\d)\d\d?/,
    q/(?<=.)(\d)\d/,
    q/(?<=\d)(\d)./,
    q/(?<=\d)(\d)\d/,
    q/(?<=\D)(\d)\d/,
    q/(?<!^)\d+(\d)/,
);

$^A = "";

for my $regex ( @regexes )
{
    my $target = $nums;
    $target =~ s/$regex/$1/g;
    formline "\$_ = '$nums'; \@<<<<<<<<<<<<<<<<<<<<<<< ".
             "# Result: \$_ eq '$target'\n", "s/$regex/\$1/g;";
    print $^A;
    $^A = "";
}