diff --git a/problem-solving/Program.cs b/problem-solving/Program.cs
index 15e54d4..3892a5c 100644
--- a/problem-solving/Program.cs
+++ b/problem-solving/Program.cs
@@ -16,85 +16,120 @@ static void Main(string[] args)
         public static long SumArray(IEnumerable<int> arr)
         {
             // return the sum of all the values in the array
-            // TODO
-            return 0;
+            return arr.Sum(i => (long)i);
         }
 
         public static long SumArrayOddValues(IEnumerable<int> arr)
         {
             // return the sum of all the values in the array that are odd
-            // TODO
-            return 0;
+            return arr.Where(value => value % 2 != 0).Sum(value => (long)value);
         }
 
         public static long SumArrayEverySecondValue(IEnumerable<int> arr)
         {
             // return the sum of every second value in the array. i.e. the 2nd value + the 4th value + the 6th value ...
-            // TODO
-            return 0;
+            return arr.Where((value, index) => index % 2 == 1).Sum(value => (long)value);
         }
 
         public static IEnumerable<int> GetUniqueValues(IEnumerable<int> arr)
         {
             // return an array that contains only unique values from the passed in array
-            // TODO
-            return null;
+            return arr.Distinct();
         }
 
         public static IEnumerable<int> GetArrayIntersect(IEnumerable<int> arrA, IEnumerable<int> arrB)
         {
             // return an array that contains all the values that are in array A and array B
-            // TODO
-            return null;
+            return arrA.Intersect(arrB);
         }
 
         public static IEnumerable<int> GetArrayNotIntersect(IEnumerable<int> arrA, IEnumerable<int> arrB)
         {
             // return an array that contains all the values that are in array A or array B but not in both array A and array B
-            // TODO
-            return null;
+            return arrA.Where(v => !arrB.Contains(v)).Union(arrB.Where(v => !arrA.Contains(v)));
         }
 
         public static Boolean HasSum(IEnumerable<int> arr, long target)
         {
+            if (arr == null)
+            {
+                throw new NullReferenceException();
+            }
             // return true if any 2 values in the array have a sum equal to the target value
             // TODO
-            return false;
+            var arrWithIndex = arr.Select((x, index) => new { val = x, ind = index });
+            return arrWithIndex.Any(val => arrWithIndex.Where(x => val.ind != x.ind).Any(val2 => val.val + val2.val == target));
         }
 
         public static long LoneSum(IEnumerable<int> arr)
         {
             // Given an array of int values, return their sum. 
             // However, if any of the values is the same as another of the values, it does not count towards the sum.
-            return 0;
+            return arr.Where(i => arr.Count(value => value == i ? true : false) == 1).Sum(value => (long)value);
         }
 
         public static String DoubleString(String s)
         {
             // return a string that is the original string with each character in the string repeated twice
             // e.g. for input "ABCDE", return "AABBCCDDEE"
-            return null;
+            if (null == s)
+            {
+                throw new ArgumentNullException();
+            }
+
+            if (String.Empty == s)
+            {
+                return String.Empty;
+            }
+            return s.ToCharArray().Select<char, String>(ch => new String(ch, 2)).Aggregate((i,j) => i + j);
         }
 
         public static int CountChars(String s, char c)
         {
+            if (s == null)
+            {
+                throw new ArgumentNullException();
+            }
             // return the count of how many times char c occurs in string s
-            return 0;
+            return s.ToCharArray().Where(ch => c == ch).Count();
         }
 
         public static long SumDigits(String s)
         {
+            if (s == null)
+            {
+                throw new ArgumentNullException();
+            }
             // return the sum of the digits 0-9 that appear in the string, ignoring all other characters
             // e.g. "123" return 6
-            return 0;
+            return s.ToCharArray().Where(ch => Char.IsDigit(ch)).Sum(value => (long)int.Parse(value.ToString()));
         }
 
         public static long SumNumbers(String s)
         {
+            if (s == null)
+            {
+                throw new ArgumentNullException();
+            }
             // return the sum of the numbers that appear in the string, ignoring all other characters
             // a number is a series of 1 or more digits in a row
             // e.g. "11 22" returns 33
-            return 0;
+            if (s.Length == 0)
+            {
+                return 0;
+            }
+
+            String strOnlyDigitsAndSpaces = s.ToCharArray()
+                .Select(ch => Char.IsDigit(ch) ? ch : ' ')
+                .Select(ch => new String(ch,1))
+                .Aggregate((str, ch) => str + "" + ch);
+
+            return strOnlyDigitsAndSpaces
+                .Split(null)
+                .Where(str => str.Length > 0)
+                .Select(str => int.Parse(str))
+                .Sum(value => (long)value);
+                
         }
 
         public static Boolean IsAnagram(String s1, String s2)
@@ -103,7 +138,7 @@ public static Boolean IsAnagram(String s1, String s2)
             // An anagram is produced by rearranging the letters of one string into another
             // e.g. care is an anagram of race
             // cat is not an anagram of rat
-            return false;
+            return s1.ToCharArray().OrderBy(ch => ch).SequenceEqual(s2.ToCharArray().OrderBy(ch => ch));
         }
 
         public static int BlackJack(int count1, int count2)
@@ -111,7 +146,9 @@ public static int BlackJack(int count1, int count2)
             // Given 2 integer values greater than 0, 
             // return whichever value is nearest to 21 without going over. 
             // Return 0 if they both go over.
-            return 0;
+            int[] cards = new int[] { count1, count2, 0 };
+            var notOver = cards.Where(v => v <= 21).OrderByDescending(c => c);
+            return notOver.First();
         }
 
         public static int FivePlayerBlackJack(int count1, int count2, int count3, int count4, int count5)
@@ -119,7 +156,9 @@ public static int FivePlayerBlackJack(int count1, int count2, int count3, int co
             // Given 5 integer values greater than 0, 
             // return whichever value is nearest to 21 without going over. 
             // Return 0 if they all go over.
-            return 0;
+            int[] cards = new int[] { count1, count2, count3, count4, count5, 0 };
+            var notOver = cards.Where(v => v <= 21).OrderByDescending(c => c);
+            return notOver.First();
         }
 
         public static int NPlayerBlackJack(IEnumerable<int> counts)
@@ -127,20 +166,25 @@ public static int NPlayerBlackJack(IEnumerable<int> counts)
             // Given a list of integer values greater than 0, 
             // return whichever value is nearest to 21 without going over. 
             // Return 0 if they all go over.
-            return 0;
+            var notOver = counts.Union(new int[]{0}).Where(v => v <= 21).OrderByDescending(c => c);
+            return notOver.First();
         }
 
         public static Dictionary<String, int> WordCount(IEnumerable<String> arr)
         {
+            if (arr == null)
+            {
+                throw new NullReferenceException();
+            }
             // Given an array of Strings, 
             // return a dictionary keyed on the string with the count of how many times each string appears in the array
-            return null;
+            return arr.Distinct().ToDictionary<string, string, int>(str => str, y => arr.Count(str => str == y));
         }
 
         public static int Factorial(int n)
         {
             // Given n, return the factorial of n, which is n * (n-1) * (n-2) ... 1
-            return 0;
+            return Enumerable.Range(1, n).Aggregate(1, (x,y) => y * x);
         }
 
         public static List<String> FB(int n)
@@ -149,7 +193,14 @@ public static List<String> FB(int n)
             // If the number is divisable by 3, replace it with the word "Fizz"
             // If the number is divisable by 5, replace it with the word "Buzz"
             // If the number is divisable by both 3 and 5, replace it with the word "FizzBuzz"
-            return null;
+            return Enumerable.Range(1, n)
+                .Select(num => 
+                    (num % 3 == 0 && num % 5 == 0) ? "FizzBuzz" 
+                    : num % 5 == 0 ? "Buzz" 
+                    : num % 3 == 0 ? "Fizz" 
+                    : num.ToString())
+                    .ToList(); 
+           
         }
     }
 }