$\ = "\n";
for $n ( 4 .. 6 ){ 
    print for '0' x $n .. '9' x $n;
}

##</code><code>##

$\ = "\n";
my @digits = 'a' .. 'j';

for my $n ( 4 .. 6 ) {
    print @digits[ split '', $_ ] 
        for '0' x $n .. '9' x $n;
}