diff --git a/MathUtilities.class b/MathUtilities.class
index 4ea9860..8f0b7d4 100644
Binary files a/MathUtilities.class and b/MathUtilities.class differ
diff --git a/MathUtilities.java b/MathUtilities.java
index 7d4f4fc..a181df9 100644
--- a/MathUtilities.java
+++ b/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 +20,7 @@ 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 +29,7 @@ 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 +38,7 @@ 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 +47,7 @@ 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 +56,7 @@ 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 +65,7 @@ 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 +74,7 @@ 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 +83,7 @@ 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 +92,7 @@ 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 +101,7 @@ 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 +110,7 @@ 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 +120,7 @@ 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 +129,7 @@ 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 +138,7 @@ 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 +147,7 @@ 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 +156,7 @@ 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 +165,7 @@ 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 +175,7 @@ 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 +184,7 @@ 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 +193,7 @@ 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 +201,7 @@ 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 +210,7 @@ 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 +219,6 @@ 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/PredicateUtilities.class b/PredicateUtilities.class
index 64dfa1b..ceee876 100644
Binary files a/PredicateUtilities.class and b/PredicateUtilities.class differ
diff --git a/PredicateUtilities.java b/PredicateUtilities.java
index 4b83a87..501d424 100644
--- a/PredicateUtilities.java
+++ b/PredicateUtilities.java
@@ -10,7 +10,7 @@ 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 +19,7 @@ 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 +28,7 @@ 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 +37,7 @@ 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;
     }
     
     
@@ -45,13 +45,13 @@ 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/StringUtilities.class b/StringUtilities.class
index 71bb6fd..01f6d5b 100644
Binary files a/StringUtilities.class and b/StringUtilities.class differ
diff --git a/StringUtilities.java b/StringUtilities.java
index b791a2a..80bbc2a 100644
--- a/StringUtilities.java
+++ b/StringUtilities.java
@@ -8,7 +8,7 @@ public class StringUtilities {
      * @return `Hello World` as a string
      */
     public static String getHelloWorld() {
-        return null;
+        return "Hello World";
     }
 
     /**
@@ -17,7 +17,7 @@ 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 +26,7 @@ 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 +34,7 @@ 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 +42,7 @@ public static String getPrefix(String input){
      * @return the last 3 characters of `input`
      */
     public static String getSuffix(String input){
-        return null;
+        return input.substring(input.length() - 3);
     }
 
     /**
@@ -51,7 +51,7 @@ 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 +59,7 @@ 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);
     }
 
     /**
@@ -67,7 +67,7 @@ public static Character getMiddleCharacter(String inputValue){
      * @return the first sequence of characters
      */
     public static String getFirstWord(String spaceDelimitedString){
-        return null;
+        return (spaceDelimitedString+" ").split(" ")[0];
     }
 
     /**
@@ -75,7 +75,7 @@ public static String getFirstWord(String spaceDelimitedString){
      * @return the second word of a string delimited by spaces.
      */
     public static String getSecondWord(String spaceDelimitedString){
-        return null;
+        return (spaceDelimitedString.split(" ")[1]);
     }
 
     /**
@@ -83,6 +83,9 @@ public static String getSecondWord(String spaceDelimitedString){
      * @return an identical string with characters in reverse order.
      */
     public static String reverse(String stringToReverse){
-        return null;
+        StringBuilder builder = new StringBuilder(stringToReverse);
+        builder.reverse();
+        
+        return builder.toString();
     }
 }
diff --git a/TestMultiplication.class b/TestMultiplication.class
index 6f83618..5971d6b 100644
Binary files a/TestMultiplication.class and b/TestMultiplication.class differ
diff --git a/TestMultiplication.java b/TestMultiplication.java
index ca937b5..770a319 100644
--- a/TestMultiplication.java
+++ b/TestMultiplication.java
@@ -48,7 +48,7 @@ public void testByteMultiplication() {
         // : Given
         byte multiplicand = 16;
         byte multiplier = 14;
-        byte expectedByte = 64;
+        byte expectedByte = -32;
         // : When
         byte actualByte = mathUtils.multiply(multiplicand, multiplier);
         // : Then