diff --git a/src/main/java/LoopFun.java b/src/main/java/LoopFun.java
index 801ab56..5fbc394 100644
--- a/src/main/java/LoopFun.java
+++ b/src/main/java/LoopFun.java
@@ -1,42 +1,63 @@
  
 
-public class LoopFun
-{
+public class LoopFun {
 
-      /**
-       * Given a number, return the factorial of that number.
-       * For example, given 5, the factorial is 5 x 4 x 3 x 2 x 1 which should return 120.
-       * @param number
-       * @return the factorial of the number
-       */
-      public Integer factorial(Integer number){
-          return null;
-      }
+    /**
+     * Given a number, return the factorial of that number.
+     * For example, given 5, the factorial is 5 x 4 x 3 x 2 x 1 which should return 120.
+     *
+     * @param number
+     * @return the factorial of the number
+     */
+    public Integer factorial(Integer number) {
+        int factorial = 1;
+        for (int i = number; i > 0; i--) {
+            factorial *= i;
+        }
+        return factorial;
+    }
 
-      /**
-       * Given a phrase, get the acronym of that phrase. Acronym is the combination of
-       * the first character of each word in upper case.
-       * For example, given "Ruby on Rails", this method will return "ROR"
-       * @param phrase
-       * @return Upper case string of the first letter of each word
-       */
-      public String acronym(String phrase) {
-          return null;
-      }
+    /**
+     * Given a phrase, get the acronym of that phrase. Acronym is the combination of
+     * the first character of each word in upper case.
+     * For example, given "Ruby on Rails", this method will return "ROR"
+     *
+     * @param phrase
+     * @return Upper case string of the first letter of each word
+     */
+    public String acronym(String phrase) {
+        //String result = phrase.replaceAll("\\B.|\\P{L}", "").toUpperCase();
+        StringBuilder initials = new StringBuilder();
+        for (String s : phrase.split(" ")){
+            initials.append(s.charAt(0));
+        }
+        return initials.toString().toUpperCase();
+    }
 
-      /**
-       * To prevent anyone from reading our messages, we can encrypt it so it will only be readable by its
-       * intended audience. This method encrypt the message by shifting the letter by 3 characters. If the character is
-       * at the end of the alphabet, it will wraps around.
-       * For example:
-       *  'a' => 'd'
-       *  'w' => 'z'
-       *  'x' => 'a'
-       *  'y' => 'b'
-       * @param word
-       * @return the encrypted string by shifting each character by three character
-       */
-      public String encrypt(String word) {
-          return null;
-      }
+    /**
+     * To prevent anyone from reading our messages, we can encrypt it so it will only be readable by its
+     * intended audience. This method encrypt the message by shifting the letter by 3 characters. If the character is
+     * at the end of the alphabet, it will wraps around.
+     * For example:
+     * 'a' => 'd'
+     * 'w' => 'z'
+     * 'x' => 'a'
+     * 'y' => 'b'
+     *
+     * @param word
+     * @return the encrypted string by shifting each character by three character
+     */
+    public String encrypt(String word) {
+        String s = "";
+        int len = word.length();
+        for (int i = 0; i < len; i++) {
+            char c = (char) (word.charAt(i) + 3);
+            if (c > 'z')
+                s += (char) (word.charAt(i) - (26 - 3));
+            else {
+                s += (char) (word.charAt(i) + 3);
+            }
+        }
+        return s;
+    }
 }
diff --git a/src/main/java/MathUtilities.java b/src/main/java/MathUtilities.java
index e067c75..daee797 100644
--- a/src/main/java/MathUtilities.java
+++ b/src/main/java/MathUtilities.java
@@ -9,7 +9,8 @@ public class MathUtilities{
    * @return the sum of the two numbers
    */
   public Integer add(Integer baseValue, Integer valueToAdd){
-      return null;
+
+      return baseValue + valueToAdd;
   }
 
   /**
@@ -19,7 +20,7 @@ public Integer add(Integer baseValue, Integer valueToAdd){
    * @return the sum of the two numbers
    */
   public Double add(Double baseValue, Double valueToAdd){
-      return null;
+      return baseValue + valueToAdd;
   }
 
   /**
@@ -28,7 +29,7 @@ public Double add(Double baseValue, Double valueToAdd){
    * @return the half of the number in double
    */
   public Double half(Integer number) {
-      return null;
+      return Double.valueOf((number / 2));
   }
 
   /**
@@ -36,8 +37,15 @@ public Double half(Integer number) {
    * @param number the number given
    * @return true if the number is odd, false if it is even
    */
-  public Boolean isOdd(Integer number){
-      return null;
+  public Boolean isOdd(Integer number) {
+
+      boolean odd = false;
+      if (number % 2 == 0) {
+          odd = false;
+      } else {
+          odd = true;
+      }
+      return odd;
   }
 
 
@@ -47,7 +55,7 @@ public Boolean isOdd(Integer number){
    * @return the result of the number multiply by itself
    */
   public Integer square(Integer number) {
-      return null;
+      return number * number;
   }
 
 }
diff --git a/src/main/java/StringUtilities.java b/src/main/java/StringUtilities.java
index e3ea8a9..81ae2ba 100644
--- a/src/main/java/StringUtilities.java
+++ b/src/main/java/StringUtilities.java
@@ -5,7 +5,7 @@ public class StringUtilities {
      * @return `input`
      */
     public String returnInput(String input) {
-        return null;
+        return input;
     }
 
     /**
@@ -14,7 +14,7 @@ public String returnInput(String input) {
      * @return the concatenation of `baseValue` and `valueToBeAdded`
      */
     public String concatenate(String baseValue, String valueToBeAdded) {
-        return null;
+        return baseValue + valueToBeAdded;
     }
 
     /**
@@ -22,7 +22,11 @@ public String concatenate(String baseValue, String valueToBeAdded) {
      * @return identical string with characters in opposite order
      */
     public String reverse(String valueToBeReversed) {
-        return null;
+        String r = "";
+        for(int i = valueToBeReversed.length() - 1; i >= 0; i--){
+            r = r + valueToBeReversed.charAt(i);
+        }
+        return r;
     }
 
     /**
@@ -30,7 +34,10 @@ public String reverse(String valueToBeReversed) {
      * @return middle character of `word`
      */
     public Character getMiddleCharacter(String word) {
-        return null;
+        int len = word.length();
+        int halfWord = len / 2;
+
+        return word.charAt(halfWord);
     }
 
     /**
@@ -39,7 +46,8 @@ public Character getMiddleCharacter(String word) {
      * @return `value` with char of value `charToRemove` removed
      */
     public String removeCharacter(String value, Character charToRemove) {
-        return null;
+        String strNew = value.replaceAll(String.valueOf(charToRemove), "");
+        return strNew;
     }
 
     /**
@@ -47,6 +55,7 @@ public String removeCharacter(String value, Character charToRemove) {
      * @return last `word` in sentence
      */
     public String getLastWord(String sentence) {
-        return null;
+        String lastWord = sentence.substring(sentence.lastIndexOf(" ")+ 1);
+        return lastWord;
     }
 }