It produces the ZERO message :) Matching the whole string produces better results:

#!/usr/local/bin/perl

use strict;
use warnings;

my $value = 10;
SWITCH: for ($value) {
    /^0\z/  && do {print "ZERO\n"; last; };
    /^1\z/  && do {print "ONE\n";  last; };
    /^10\z/ && do {print "TEN\n";  last; };
                print "NONE OF THE ABOVE\n";
}
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