Pseudo-code

I think...unless columns and word-searchiness is allowed (eg diagonals) or snake-iness, //read in first thirteen numbers //find product of those numbers //read in next thirteen numbers and do the same //if the product is larger than the previous product //is more than the previous product
//replace the old product with new product //keep going until you run out of input file-ness :)

--Possible Haskell-esque/functionally solution --Split every thirteen values (will give an array for each one) --Map over each array separately with foldl1(*) and get product

?use partition, take items and fold * => Clojure or Haskell