A Regular Expression to Check if a Number is Prime
/^1?$|^(11+?)\1+$/
usage:
perl -wle 'print "Prime" if (1 x shift) !~ /^1?$|^(11+?)\1+$/' [number]
more
usage:
perl -wle 'print "Prime" if (1 x shift) !~ /^1?$|^(11+?)\1+$/' [number]
more

