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..687ec67 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 +11,8 @@ public class MathUtilities {
      * @return sum of `baseValue` and `difference`
      */
     public Integer add(int baseValue, int difference) {
-        return null;
+
+        return baseValue + difference;
     }
 
     /**
@@ -20,7 +21,8 @@ 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 +31,10 @@ public Long add(long baseValue, long difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Short add(short baseValue, short difference) {
-        return null;
+
+    int first = baseValue + difference;
+    short s = (short) first;
+    return s;
     }
 
     /**
@@ -38,7 +43,9 @@ public Short add(short baseValue, short difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Byte add(byte baseValue, byte difference) {
-        return null;
+        int first = baseValue + difference;
+        byte s = (byte) first;
+        return s;
     }
 
     /**
@@ -47,7 +54,9 @@ 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 +65,7 @@ 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 +74,8 @@ 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 +84,8 @@ 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 +94,9 @@ public Long subtract(long baseValue, long difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Short subtract(short baseValue, short difference) {
-        return null;
+       int subtract = baseValue - difference;
+       short s = (short) subtract;
+        return s;
     }
 
     /**
@@ -92,7 +105,9 @@ public Short subtract(short baseValue, short difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Byte subtract(byte baseValue, byte difference) {
-        return null;
+        int subtract = baseValue - difference;
+        byte s = (byte) subtract;
+        return s;
     }
 
     /**
@@ -101,7 +116,8 @@ 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 +126,7 @@ 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 +136,8 @@ 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 +146,7 @@ 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 +155,9 @@ public Long divide(long dividend, long divisor) {
      * @return division of `dividend` by `divisor
      */
     public Short divide(short dividend, short divisor) {
-        return null;
+        int result = dividend/divisor;
+        short s = (short) result;
+        return s;
     }
 
     /**
@@ -147,7 +166,9 @@ public Short divide(short dividend, short divisor) {
      * @return division of `dividend` by `divisor
      */
     public Byte divide(byte dividend, byte divisor) {
-        return null;
+        int result = dividend/divisor;
+        byte s = (byte) result;
+        return s;
     }
 
     /**
@@ -156,7 +177,7 @@ 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 +186,7 @@ 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 +196,7 @@ 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 +205,7 @@ 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 +214,10 @@ public Long multiply(long multiplicand, long multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Short multiply(short multiplicand, short multiplier) {
-        return null;
+        int result = multiplicand * multiplier;
+        short s = (short) result;
+
+        return s;
     }
     /**
      * @param multiplicand value to be multiplied
@@ -201,7 +225,10 @@ public Short multiply(short multiplicand, short multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Byte multiply(byte multiplicand, byte multiplier) {
-        return null;
+        int result = multiplicand * multiplier;
+        byte s = (byte) result;
+
+        return s;
     }
 
     /**
@@ -210,7 +237,7 @@ 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 +246,6 @@ 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/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..f457fc5 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
@@ -10,25 +10,34 @@ public class PredicateUtilities {
      * @return true if `x` is greater than `y`
      */
     public Boolean isGreaterThan(int x, int y) {
-        return null;
-    }
+        if (x > y) {
 
+        }
+        return true;
+    }
     /**
      * @param x
      * @param y
      * @return true if `x` is less than `y`
      */
-    public Boolean isLessThan(int x, int y) {
-        return null;
-    }
-
+    public Boolean isLessThan(int x, int y){
+            if (x < y) ;
+            {
+                return true;
+            }
+        }
     /**
      * @param x
      * @param y
      * @return true if `x` is greater than or equal to `y`
      */
     public Boolean isGreaterThanOrEqualTo(int x, int y) {
-        return null;
+        if (x >= y) {
+
+        };
+        return true;
+
+
     }
 
     /**
@@ -37,7 +46,11 @@ 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;
+       if (x <= y) {
+
+       }
+
+        return true;
     }
 
 
@@ -45,14 +58,14 @@ 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..8c5a95e 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
@@ -4,11 +4,9 @@
  * Created by dan on 6/14/17.
  */
 public class StringUtilities {
-    /**
-     * @return `Hello World` as a string
-     */
+
     public static String getHelloWorld() {
-        return null;
+        return "Hello World";
     }
 
     /**
@@ -17,7 +15,8 @@ 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.concat(secondSegment);
     }
 
     /**
@@ -26,7 +25,8 @@ 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 +34,8 @@ 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(0,2);
     }
 
     /**
@@ -42,8 +43,17 @@ public static String getPrefix(String input){
      * @return the last 3 characters of `input`
      */
     public static String getSuffix(String input){
-        return null;
-    }
+            if ( input.length() < 3) {
+                return input;
+            } else {
+                return input.substring(input.length()-3);
+            }
+
+
+        }
+
+
+
 
     /**
      * @param inputValue the value to be compared
@@ -51,7 +61,7 @@ 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 == comparableValue);
     }
 
     /**
@@ -59,7 +69,9 @@ 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()/2);
     }
 
     /**
@@ -67,7 +79,9 @@ public static Character getMiddleCharacter(String inputValue){
      * @return the first sequence of characters
      */
     public static String getFirstWord(String spaceDelimitedString){
-        return null;
+        int i = spaceDelimitedString.indexOf(' ');
+        String coffee = spaceDelimitedString.substring(0, i);
+        return coffee;
     }
 
     /**
@@ -83,6 +97,15 @@ public static String getSecondWord(String spaceDelimitedString){
      * @return an identical string with characters in reverse order.
      */
     public static String reverse(String stringToReverse){
-        return null;
+
+
+        String output = "";
+
+        for (int i = stringToReverse.length() - 1; i > 0; i--) {
+            output += stringToReverse.charAt(i);
+        }
+            return output;
+
+
     }
 }