This doesn't happen. If you are seeing it then it is something you are doing wrong in your code. Run my sample script and see for yourself:

#!/usr/bin/perl
use strict;
use warnings;

while ( <DATA> ) {
    chomp;
    print format_it( split " " , $_ ), "\n";
}

sub format_it {
    my $formatted;
    for ( @_ ) {
        $formatted .= length $_ == 1 ? '0' . $_ : $_;
    }
    return $formatted;
}

__DATA__
3 2 61
13
333
5
7
8
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