Quick fix:

sub RabinMiller
{
    my $p = shift;
    my $b = 0;
    my $m = $p - 1;
    my $t = 20; # The probability of error is .25 ** $t
                # Probability of error with $t = 20 is lt 10 ** -12.
    return 0 if ($p % 2 == 0 && $p > 2);
    .....
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