Calculates the product of 13 adjacent numbers and returns the largest product. Yeah didn't comment this one. Simple iterate through all.
To make better...recognize that if you encounter a 0 you can skip the next 13 products.
That you can compare the last first digit with the new last digit (whichever is larger that entire product will be larger and therefore we can compare digits instead of multiplying them and comparing them). this comparision data would have to be stored somehow...in a tree maybe? i was thinking about how to approach this problem...

deemed it unnecessary and we can just iterate through...though for huge numbers it would definitely be better.