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..2a06dcd 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
@@ -11,7 +11,7 @@ public class MathUtilities {
      * @return sum of `baseValue` and `difference`
      */
     public Integer add(int baseValue, int difference) {
-        return null;
+        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 +30,8 @@ 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 +40,8 @@ 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 +50,8 @@ 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 +60,8 @@ 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 +70,8 @@ public Double add(double baseValue, double difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Integer subtract(int baseValue, int difference) {
-        return null;
+
+        return (int) (baseValue - difference);
     }
 
     /**
@@ -74,7 +80,8 @@ 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 +90,8 @@ 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 +100,8 @@ 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 +110,8 @@ 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 +120,8 @@ 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 +131,8 @@ public Double subtract(double baseValue, double difference) {
      * @return division of `dividend` by `divisor
      */
     public Integer divide(int dividend, int divisor) {
-        return null;
+
+        return (int) (dividend/divisor);
     }
 
     /**
@@ -129,7 +141,8 @@ 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 +151,8 @@ 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 +161,8 @@ 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 +171,8 @@ 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 +181,8 @@ 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 +192,8 @@ public Double divide(double dividend, double divisor) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Integer multiply(int multiplicand, int multiplier) {
-        return null;
+
+        return (int) (multiplicand*multiplier);
     }
 
     /**
@@ -184,7 +202,8 @@ 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 +212,8 @@ 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 +221,8 @@ 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 +231,8 @@ 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 +241,7 @@ 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..69f0d0d 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..106ba86 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;
+
+        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 +46,10 @@ public static String getPrefix(String input){
      * @return the last 3 characters of `input`
      */
     public static String getSuffix(String input){
-        return null;
+
+        int a = input.length();
+        int b = input.length() - 3;
+        return input.substring(b, a);
     }
 
     /**
@@ -51,7 +58,8 @@ 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 +67,13 @@ public static Boolean compareTwoStrings(String inputValue, String comparableValu
      * @return the middle character of `inputValue`
      */
     public static Character getMiddleCharacter(String inputValue){
-        return null;
+
+        int a = inputValue.length();
+        int i;
+        if (a%2==0) {i=a/2 - 1;}
+        else {i = a/2;}
+
+        return inputValue.charAt(i);
     }
 
     /**
@@ -67,7 +81,9 @@ public static Character getMiddleCharacter(String inputValue){
      * @return the first sequence of characters
      */
     public static String getFirstWord(String spaceDelimitedString){
-        return null;
+
+        String a[] = spaceDelimitedString.split(" ");
+        return a [0];
     }
 
     /**
@@ -75,7 +91,8 @@ public static String getFirstWord(String spaceDelimitedString){
      * @return the second word of a string delimited by spaces.
      */
     public static String getSecondWord(String spaceDelimitedString){
-        return null;
+        String a[] = spaceDelimitedString.split(" ");
+        return a [1];
     }
 
     /**
@@ -83,6 +100,6 @@ public static String getSecondWord(String spaceDelimitedString){
      * @return an identical string with characters in reverse order.
      */
     public static String reverse(String stringToReverse){
-        return null;
+        return new StringBuffer(stringToReverse).reverse().toString();
     }
 }
diff --git a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/ZipcodeRocks.java b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/ZipcodeRocks.java
index 819f21b..fdef5bb 100644
--- a/src/main/java/com/zipcodewilmington/danny_do_better_exercises/ZipcodeRocks.java
+++ b/src/main/java/com/zipcodewilmington/danny_do_better_exercises/ZipcodeRocks.java
@@ -5,6 +5,6 @@
  */
 public class ZipcodeRocks {
     public static void main(String[] args) {
-//         System.out.println("Zipcode Rocks!");
+         System.out.println("Zipcode Rocks!");
     }
 }