Simple prime checker

prime.pl

#!/usr/bin/perl

use warnings;
use strict;

while(<DATA>) {
  chomp;

  my $flag = 1;
  foreach my $i (2 .. sqrt($_)) {
    unless ($_ % $i) {
      $flag = 0;
      last;
    }
  }
  print "Number $_ ";
  if ($flag) {
    print "prime";
  } else {
    print "not prime";
  }
  print "\n";
}

__END__
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