Hello, I'm trying to solve Euler problem 104 with the solution "My Solution" below but it takes quite long time therefore I quite. Then I turn to haskell wiki for better solution which work well but I can not figure out why it is better than mine. I'm wondering whether more function call decrease the performance. Could you please help a little? Thank you. *-- | My Solution * main = print $ snd $ head $ dropWhile (\(x,y) -> (not . bothNinePandigit "123456789") x) (zip fibs [1..]) bothNinePandigit digits n = isFirstNinePandigit digits n && isLastNinePandigit digits n isLastNinePandigit digits n = digits == sort (lastDigits 9 n) isFirstNinePandigit digits n = digits == sort (firstDigits 9 n) firstDigits k n = take k (show n) lastDigits k n = show (n `mod` 10^k) fibs = 0 : 1 : zipWith (+) fibs (tail fibs) *-- | From Haskell Wiki * fibs = 1 : 1 : zipWith (+) fibs (tail fibs) isFibPan n = let a = n `mod` 1000000000 b = sort (show a) c = sort $ take 9 $ show n in b == "123456789" && c == "123456789" ex_104 = snd $ head $ dropWhile (\(x,y) -> (not . isFibPan) x) (zip fibs [1..])