http://www.perlmonks.org?node_id=143959


in reply to Prime Number Finder

You may as well write 
for($i=$o; $i<=$e; $i++){

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as 
print "2 is prime\n" if $o == 2;
$o++ if $o % 2;
for my $i ( $i=$o; $i<=$e; $i+=2 ){

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That way you start on an odd number and account for the only even number which is prime. There is no need to check even numbers after 2.

In Section Cool Uses for Perl