diff --git a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/MathUtilities.java b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/MathUtilities.java
index 8076dfe..5f4e99a 100644
--- a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/MathUtilities.java
+++ b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/MathUtilities.java
@@ -10,8 +10,8 @@ public class MathUtilities {
      * @param difference value to add to starting value
      * @return sum of `baseValue` and `difference`
      */
-    public Integer add(int baseValue, int difference) {
-        return null;
+    public Integer add(int baseValue, int difference){
+        return baseValue + difference;
     }
 
     /**
@@ -20,7 +20,8 @@ public Integer add(int baseValue, int difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Long add(long baseValue, long difference) {
-        return null;
+
+        return baseValue + difference;
     }
 
     /**
@@ -29,7 +30,7 @@ public Long add(long baseValue, long difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Short add(short baseValue, short difference) {
-        return null;
+        return (short) (baseValue + difference);
     }
 
     /**
@@ -38,7 +39,8 @@ public Short add(short baseValue, short difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Byte add(byte baseValue, byte difference) {
-        return null;
+
+        return (byte) (baseValue + difference);
     }
 
     /**
@@ -47,7 +49,8 @@ public Byte add(byte baseValue, byte difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Float add(float baseValue, float difference) {
-        return null;
+
+        return baseValue + difference;
     }
 
     /**
@@ -56,7 +59,8 @@ public Float add(float baseValue, float difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Double add(double baseValue, double difference) {
-        return null;
+
+        return baseValue + difference;
     }
 
     /**
@@ -65,7 +69,8 @@ public Double add(double baseValue, double difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Integer subtract(int baseValue, int difference) {
-        return null;
+
+        return baseValue - difference;
     }
 
     /**
@@ -74,7 +79,8 @@ public Integer subtract(int baseValue, int difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Long subtract(long baseValue, long difference) {
-        return null;
+
+        return baseValue - difference;
     }
 
     /**
@@ -83,7 +89,8 @@ public Long subtract(long baseValue, long difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Short subtract(short baseValue, short difference) {
-        return null;
+
+        return (short) (baseValue - difference);
     }
 
     /**
@@ -92,7 +99,8 @@ public Short subtract(short baseValue, short difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Byte subtract(byte baseValue, byte difference) {
-        return null;
+
+        return (byte) (baseValue - difference);
     }
 
     /**
@@ -101,7 +109,8 @@ public Byte subtract(byte baseValue, byte difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Float subtract(float baseValue, float difference) {
-        return null;
+
+        return baseValue - difference;
     }
 
     /**
@@ -110,7 +119,8 @@ public Float subtract(float baseValue, float difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Double subtract(double baseValue, double difference) {
-        return null;
+
+        return baseValue - difference;
     }
 
 
@@ -120,7 +130,8 @@ public Double subtract(double baseValue, double difference) {
      * @return division of `dividend` by `divisor
      */
     public Integer divide(int dividend, int divisor) {
-        return null;
+
+        return dividend / divisor;
     }
 
     /**
@@ -129,7 +140,8 @@ public Integer divide(int dividend, int divisor) {
      * @return division of `dividend` by `divisor
      */
     public Long divide(long dividend, long divisor) {
-        return null;
+
+        return dividend / divisor;
     }
 
     /**
@@ -138,7 +150,8 @@ public Long divide(long dividend, long divisor) {
      * @return division of `dividend` by `divisor
      */
     public Short divide(short dividend, short divisor) {
-        return null;
+
+        return (short) (dividend / divisor);
     }
 
     /**
@@ -147,7 +160,8 @@ public Short divide(short dividend, short divisor) {
      * @return division of `dividend` by `divisor
      */
     public Byte divide(byte dividend, byte divisor) {
-        return null;
+
+        return (byte) (dividend / divisor);
     }
 
     /**
@@ -156,7 +170,8 @@ public Byte divide(byte dividend, byte divisor) {
      * @return division of `dividend` by `divisor
      */
     public Float divide(float dividend, float divisor) {
-        return null;
+
+        return dividend / divisor;
     }
 
     /**
@@ -165,7 +180,8 @@ public Float divide(float dividend, float divisor) {
      * @return division of `dividend` by `divisor
      */
     public Double divide(double dividend, double divisor) {
-        return null;
+
+        return dividend / divisor;
     }
 
 
@@ -175,7 +191,8 @@ public Double divide(double dividend, double divisor) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Integer multiply(int multiplicand, int multiplier) {
-        return null;
+
+        return multiplicand * multiplier;
     }
 
     /**
@@ -184,7 +201,8 @@ public Integer multiply(int multiplicand, int multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Long multiply(long multiplicand, long multiplier) {
-        return null;
+
+        return multiplicand * multiplier;
     }
 
     /**
@@ -193,7 +211,8 @@ public Long multiply(long multiplicand, long multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Short multiply(short multiplicand, short multiplier) {
-        return null;
+
+        return (short) (multiplicand * multiplier);
     }
     /**
      * @param multiplicand value to be multiplied
@@ -201,7 +220,8 @@ public Short multiply(short multiplicand, short multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Byte multiply(byte multiplicand, byte multiplier) {
-        return null;
+
+        return (byte) (multiplicand * multiplier);
     }
 
     /**
@@ -210,7 +230,8 @@ public Byte multiply(byte multiplicand, byte multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Float multiply(float multiplicand, float multiplier) {
-        return null;
+
+        return multiplicand * multiplier;
     }
 
     /**
@@ -219,6 +240,7 @@ public Float multiply(float multiplicand, float multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Double multiply(double multiplicand, double multiplier) {
-        return null;
+
+        return multiplicand * multiplier;
     }
 }
diff --git a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/PredicateUtilities.java b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/PredicateUtilities.java
index cb5f822..981bba1 100644
--- a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/PredicateUtilities.java
+++ b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/PredicateUtilities.java
@@ -10,7 +10,8 @@ public class PredicateUtilities {
      * @return true if `x` is greater than `y`
      */
     public Boolean isGreaterThan(int x, int y) {
-        return null;
+
+        return x > y;
     }
 
     /**
@@ -19,7 +20,8 @@ public Boolean isGreaterThan(int x, int y) {
      * @return true if `x` is less than `y`
      */
     public Boolean isLessThan(int x, int y) {
-        return null;
+
+        return x < y;
     }
 
     /**
@@ -28,7 +30,8 @@ public Boolean isLessThan(int x, int y) {
      * @return true if `x` is greater than or equal to `y`
      */
     public Boolean isGreaterThanOrEqualTo(int x, int y) {
-        return null;
+
+        return x >= y;
     }
 
     /**
@@ -37,7 +40,8 @@ public Boolean isGreaterThanOrEqualTo(int x, int y) {
      * @return true if `x` is less than or equal to `y`
      */
     public Boolean isLessThanOrEqualTo(int x, int y) {
-        return null;
+
+        return x <= y;
     }
 
 
@@ -45,14 +49,16 @@ public Boolean isLessThanOrEqualTo(int x, int y) {
      * @return true
      */
     public Boolean returnTrue() {
-        return null;
+
+        return true;
     }
 
     /**
      * @return false
      */
     public Boolean returnFalse() {
-        return null;
+
+        return false;
     }
 
-}
\ No newline at end of file
+}
diff --git a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/StringUtilities.java b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/StringUtilities.java
index 2f776a9..457818f 100644
--- a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/StringUtilities.java
+++ b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/StringUtilities.java
@@ -8,7 +8,8 @@ public class StringUtilities {
      * @return `Hello World` as a string
      */
     public static String getHelloWorld() {
-        return null;
+
+        return "Hello World";
     }
 
     /**
@@ -17,7 +18,8 @@ public static String getHelloWorld() {
      * @return the concatenation of two strings, `firstSegment`, and `secondSegment`
      */
     public static String concatenation(String firstSegment, String secondSegment){
-        return null;
+
+        return firstSegment + secondSegment;
     }
 
     /**
@@ -26,7 +28,8 @@ public static String concatenation(String firstSegment, String secondSegment){
      * @return the concatenation of an integer, `firstSegment`, and a String, `secondSegment`
      */
     public static String concatenation(int firstSegment, String secondSegment){
-        return null;
+        //String strFirst =
+        return firstSegment + secondSegment;
     }
 
     /**
@@ -34,7 +37,8 @@ public static String concatenation(int firstSegment, String secondSegment){
      * @return the first 3 characters of `input`
      */
     public static String getPrefix(String input){
-        return null;
+
+        return input.substring(0, 3);
     }
 
     /**
@@ -42,7 +46,9 @@ public static String getPrefix(String input){
      * @return the last 3 characters of `input`
      */
     public static String getSuffix(String input){
-        return null;
+        int lengthMinus = input.length() - 3;
+        int length = input.length();
+        return input.substring(lengthMinus, length);
     }
 
     /**
@@ -51,7 +57,8 @@ public static String getSuffix(String input){
      * @return the equivalence of two strings, `inputValue` and `comparableValue`
      */
     public static Boolean compareTwoStrings(String inputValue, String comparableValue){
-        return null;
+
+        return inputValue.equals(comparableValue);
     }
 
     /**
@@ -59,7 +66,8 @@ public static Boolean compareTwoStrings(String inputValue, String comparableValu
      * @return the middle character of `inputValue`
      */
     public static Character getMiddleCharacter(String inputValue){
-        return null;
+
+        return inputValue.charAt((inputValue.length() - 1) / 2);
     }
 
     /**
@@ -67,15 +75,17 @@ public static Character getMiddleCharacter(String inputValue){
      * @return the first sequence of characters
      */
     public static String getFirstWord(String spaceDelimitedString){
-        return null;
+        String[] senArray = spaceDelimitedString.split(" ");
+        return senArray[0];
     }
 
     /**
      * @param spaceDelimitedString a string delimited by spaces
      * @return the second word of a string delimited by spaces.
      */
-    public static String getSecondWord(String spaceDelimitedString){
-        return null;
+    public static String getSecondWord(String spaceDelimitedString) {
+        String[] senArray = spaceDelimitedString.split(" ");
+        return senArray[1];
     }
 
     /**
@@ -83,6 +93,14 @@ public static String getSecondWord(String spaceDelimitedString){
      * @return an identical string with characters in reverse order.
      */
     public static String reverse(String stringToReverse){
-        return null;
+        char[] inStrArr = stringToReverse.toCharArray();
+        char[] outStrArr = new char[inStrArr.length];
+        int j = 0;
+        for (int i = inStrArr.length -1; i >= 0; i--) {
+            outStrArr[j] = inStrArr[i];
+            j++;
+        }
+        String revOutStr = String.valueOf(outStrArr);
+        return revOutStr;
     }
 }