This is a cross-number puzzle that requires Web searches to find the necessary information.Much of it involves finding information about special numbers e.g. Armstrong Numbers, Golden Primes, Repdigits, Vampire numbers and their Fangs, Tribonacci Numbers, Beastly Numbers, Smith Numbers and the Smith Brothers. Primes, squares, cubes and perfect numbers also get a look-in along with the idea of permutations. And who is Kaprekar and what is his routine?A demanding fun-packed puzzle that should keep