It isn't clear from your description what the vietnamese for '110' is. Should it be 'mot tram mot muoi', or 'mot tram muoi'? If it's the former, the following fix will work:

use strict;
use warnings 'all';
my %numbers = (
    0,    '',    1, 'mot',  2,  'hai',  3,   'ba',
    4,    'bon', 5, 'nam',  6,  'sau',  7,   'bay',
    8,    'tam', 9, 'chin', 10, 'muoi', 100, 'tram',
    1000, 'ngan'
  );
          
  sub translate {
    my $number = $_[0];
    my @output = ();
    if (defined($numbers{$number})) {
      my $text_version = $numbers{$number};
      print "$text_version \n";
    } else {
      my $reverse_number = reverse($number);
      my $places         = 1;
      my @digits         = split ('', $reverse_number);
      foreach my $digit (@digits) {
        next unless $digit;
        if ($places == 1) {
          push (@output, $numbers{$digit});
        } else {
          push (@output, $numbers{$places});
          unless ($number < 20) {
            push (@output, $numbers{$digit});
          }
        }
      }
      continue {
        $places *= 10;
      }
      @output = reverse(@output);
      print "@output \n";
    }
  }
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You were having a problem for dealing with the digit '0'. You were parsing '101' as '1 times 100, 0 times 10, and 1', and the '0 times 10' was emitted as "vietnamese for zero" followed by "vietnamese for ten", resulting in "muoi".

Abigail