diff --git a/src/main/java/LoopFun.java b/src/main/java/LoopFun.java
index 801ab56..a1e8d30 100644
--- a/src/main/java/LoopFun.java
+++ b/src/main/java/LoopFun.java
@@ -10,7 +10,17 @@ public class LoopFun
        * @return the factorial of the number
        */
       public Integer factorial(Integer number){
-          return null;
+          int result = 1;
+          for (int i = number; i > 0; i--) {
+              result = result * i;
+          }
+          return result;
+
+//          if (number==0)
+//              return 1;
+//          else {
+//              return (number * factorial(number-1));
+//          }
       }
 
       /**
@@ -21,7 +31,18 @@ public Integer factorial(Integer number){
        * @return Upper case string of the first letter of each word
        */
       public String acronym(String phrase) {
-          return null;
+
+//          String str = phrase.replaceAll("\\B.|\\P{L}", "").toUpperCase();
+//          return str;
+
+          String variable = "";
+          String[] a = phrase.split(" "); // hello my name > [hello, my, name]
+          for (int i=0; i<a.length; i++){
+              variable = variable + a[i].charAt(0);
+          }
+          variable = variable.toUpperCase();
+          return variable;
+
       }
 
       /**
@@ -37,6 +58,16 @@ public String acronym(String phrase) {
        * @return the encrypted string by shifting each character by three character
        */
       public String encrypt(String word) {
-          return null;
+          char[] chars = word.toCharArray();
+          String result = "";
+          for (int i = 0; i < chars.length; i++) {
+              if(chars[i] <= 'w') {
+                  result += chars[i] += 3;
+              } else if (chars[i] >= 'x') {
+                  result += chars[i] -= 23;
+              }
+          }
+
+          return result;
       }
 }
diff --git a/src/main/java/MathUtilities.java b/src/main/java/MathUtilities.java
index e067c75..b97717a 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;
+      int sum = baseValue+valueToAdd;
+      return sum;
   }
 
   /**
@@ -19,7 +20,8 @@ public Integer add(Integer baseValue, Integer valueToAdd){
    * @return the sum of the two numbers
    */
   public Double add(Double baseValue, Double valueToAdd){
-      return null;
+      double sum = baseValue+valueToAdd;
+      return sum;
   }
 
   /**
@@ -28,7 +30,8 @@ public Double add(Double baseValue, Double valueToAdd){
    * @return the half of the number in double
    */
   public Double half(Integer number) {
-      return null;
+      double answer = number/2;
+      return (answer);
   }
 
   /**
@@ -37,7 +40,7 @@ public Double half(Integer number) {
    * @return true if the number is odd, false if it is even
    */
   public Boolean isOdd(Integer number){
-      return null;
+      return (number % 2 != 0);
   }
 
 
@@ -47,7 +50,7 @@ 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..28c393e 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 +22,12 @@ public String concatenate(String baseValue, String valueToBeAdded) {
      * @return identical string with characters in opposite order
      */
     public String reverse(String valueToBeReversed) {
-        return null;
+        String input = valueToBeReversed;
+        StringBuilder answer = new StringBuilder();
+        answer.append(input);
+        answer.reverse();
+
+        return answer.toString();
     }
 
     /**
@@ -30,7 +35,9 @@ public String reverse(String valueToBeReversed) {
      * @return middle character of `word`
      */
     public Character getMiddleCharacter(String word) {
-        return null;
+        int length = word.length();
+        int middle = length/2;
+        return word.charAt(middle);
     }
 
     /**
@@ -39,7 +46,14 @@ public Character getMiddleCharacter(String word) {
      * @return `value` with char of value `charToRemove` removed
      */
     public String removeCharacter(String value, Character charToRemove) {
-        return null;
+        char[] characters = value.toCharArray();
+        String result = "";
+        for(int i = 0; i < characters.length; i++) {
+            if (characters[i] != charToRemove) {
+                result += characters[i];
+            }
+        }
+        return result;
     }
 
     /**
@@ -47,6 +61,7 @@ public String removeCharacter(String value, Character charToRemove) {
      * @return last `word` in sentence
      */
     public String getLastWord(String sentence) {
-        return null;
+        String[] word = sentence.split(" ");
+        return word[word.length-1];
     }
 }