note ferrency Here is a prime number verifier that Abigail presented at his talk entitled <a href=> "JAPHs and Other Obscure Signatures"</a> at YAPC 19100. Very clever, very short, but I can't say much for the performance: <code> perl -wle 'print "Prime" if (1 x shift) !~ /^1?$|^(11+?)\1+$/' </code> This takes a number as a parameter, and checks to see whether it's prime or not. I modified it a bit to stuff @_ with primes, and got this:<p> <code> for(1..100){push@_,$_ if (1 x $_) !~ /^1?$|^(11+?)\1+$/} </code> I think that's shorter, no?<br> As I said, I can't claim credit for this! But it's definitely worth noting. There's an explanation of how it works on his talk web site. <p> Alan 20633 20633