diff --git a/5-recursion.hs b/5-recursion.hs
index 6baea90..b7056a9 100644
--- a/5-recursion.hs
+++ b/5-recursion.hs
@@ -1,19 +1,18 @@
 -- Raise x to the power y, using recursion
 -- For example, power 5 2 = 25
 power :: Int -> Int -> Int
-power x y = undefined
+power x 1 = x
+power x y = x * power x (y-1)
 
 -- create a list of length n of the fibbonaci sequence in reverse order
 -- examples: fib 0 = [0]
 -- 	     fib 1 = [1, 0]
---	     fib 10 = [55,34,21,13,8,5,3,2,1,1,0]	
+--	     fib 10 = [55,34,21,13,8,5,3,2,1,1,0]
 -- try to use a where clause
 fib :: (Num a, Eq a) => a -> [a]
 fib 0 = [0]
 fib 1 = [1, 0]
-fib n = head prev + head prev2 : prev
-        where prev = fib (n-1)
-              prev2 = fib (n-2)
+fib n = let all@(x:y:_) = fib (n-1) in (x+y):all
 
 -- This is not recursive, but have a go anyway.
 -- Create a function which takes two parameters, a number and a step
@@ -22,9 +21,9 @@ fib n = head prev + head prev2 : prev
 --			    stepReverseSign -3 1 = 4
 --			    stepReverseSign 1 2 = -3
 stepReverseSign :: (Fractional a, Ord a) => a -> a -> a
-stepReverseSign num step = ((if num > 0
-                        then -1
-                        else 1) * (abs(num) + step))
+stepReverseSign num step
+  | num < 0 = (abs num) + step
+  | otherwise = (-1) * (num + step)
 
 {- Lets calculate pi.
  - The Leibniz formula for pi (http://en.wikipedia.org/wiki/Leibniz_formula_for_%CF%80)
@@ -42,7 +41,7 @@ stepReverseSign num step = ((if num > 0
  - snd is the number of recursive steps taken to calculate it, after all this chapter is about recursion!
  - Example: piCalc 0.001 = (3.1420924036835256,2000)
 
- - The piCalc' function is defined as 
+ - The piCalc' function is defined as
  - piCalc' :: (Ord a, Fractional a, Integral b) => a -> a -> a -> b -> (a, b)
  - Lots of parameters!
  - The first parameter is the current denominator from the Leibniz formula
@@ -53,7 +52,7 @@ stepReverseSign num step = ((if num > 0
  -
  - Feel free to change the parameter order, what parameters you need etc in order to get this to work for you,
  - But, of course the output of piCalc should remain as (pi, count)
- - 
+ -
  - You may find the stepReverseSign function handy
  -}
 
@@ -62,8 +61,6 @@ piCalc tolerance = piCalc' 1 0.0 tolerance 0
 
 piCalc' :: (Ord a, Fractional a, Integral b) => a -> a -> a -> b -> (a, b)
 piCalc' denom prevPi tolerance count = if abs(newPi - prevPi) < tolerance
-                                        then (newPi, count)
-                                        else piCalc' (stepReverseSign denom) newPi tolerance (count + 1)
-                                        where newPi = prevPi + (4 / denom)
-
-
+                                       then (newPi, count)
+                                       else piCalc' (stepReverseSign denom 2) newPi tolerance (count + 1)
+                                       where newPi = prevPi + (4 / denom)