I guess I should warn that these Project Euler posts have **spoilers**, in case you want to try the problems yourself ☺. My Scala solution to problem 8:

val input = "73167176531330624919225119674426574742355349194934" + "96983520312774506326239578318016984801869478851843" + "85861560789112949495459501737958331952853208805511" + "12540698747158523863050715693290963295227443043557" + "66896648950445244523161731856403098711121722383113" + "62229893423380308135336276614282806444486645238749" + "30358907296290491560440772390713810515859307960866" + "70172427121883998797908792274921901699720888093776" + "65727333001053367881220235421809751254540594752243" + "52584907711670556013604839586446706324415722155397" + "53697817977846174064955149290862569321978468622482" + "83972241375657056057490261407972968652414535100474" + "82166370484403199890008895243450658541227588666881" + "16427171479924442928230863465674813919123162824586" + "17866458359124566529476545682848912883142607690042" + "24219022671055626321111109370544217506941658960408" + "07198403850962455444362981230987879927244284909188" + "84580156166097919133875499200524063689912560717606" + "05886116467109405077541002256983155200055935729725" + "71636269561882670428252483600823257530420752963450" val digits = input.map(_.asDigit).toArray def multiply(index: Int) = digits.slice(index, index + 5) .foldLeft(1)(_*_) val multiples: Stream[Int] = { def rec(n: Int): Stream[Int] = Stream.cons(multiply(n), if (n > digits.length - 5) Stream.empty else rec(n+1)) Stream.cons(mult(0), rec(1)) } println(Iterable.max(multiples))

For convenience, this specifies the input as a string, then uses `RichChar.asDigit`

to create a corresponding array of integers. The `multiply`

function uses left fold to multiply together sequences of five digits. The `multiples`

value is a stream (lazy list) of the multiples of all groups of five consecutive digits from the input. And finally, the `Iterable`

object provides a convenient method to find the maximum value in any Iterable containing Orderable things.