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src/main/java/com/zipcodewilmington/danny_do_better_exercises/MathUtilities.java

      * @return sum of `baseValue` and `difference`
      */
     public Integer add(int baseValue, int difference) {
-        return null;
+        return baseValue + difference;
     }
 
     /**
      * @return sum of `baseValue` and `difference`
      */
     public Long add(long baseValue, long difference) {
-        return null;
+       return baseValue + difference;
     }
 
     /**
      * @return sum of `baseValue` and `difference`
      */
     public Short add(short baseValue, short difference) {
-        return null;
+        return (short)(baseValue + difference);
     }
 
     /**
      * @return sum of `baseValue` and `difference`
      */
     public Byte add(byte baseValue, byte difference) {
-        return null;
+        return (byte)(baseValue + difference);
     }
 
     /**
      * @return sum of `baseValue` and `difference`
      */
     public Float add(float baseValue, float difference) {
-        return null;
+        return baseValue + difference;
     }
 
     /**
      * @return sum of `baseValue` and `difference`
      */
     public Double add(double baseValue, double difference) {
-        return null;
+        return (baseValue + difference);
     }
 
     /**
      * @return difference between `baseValue` and `difference`
      */
     public Integer subtract(int baseValue, int difference) {
-        return null;
+        return baseValue - difference;
     }
 
     /**
      * @return difference between `baseValue` and `difference`
      */
     public Long subtract(long baseValue, long difference) {
-        return null;
+        return baseValue - difference;
     }
 
     /**
      * @return difference between `baseValue` and `difference`
      */
     public Short subtract(short baseValue, short difference) {
-        return null;
+        return (short)(baseValue - difference);
     }
 
     /**
      * @return difference between `baseValue` and `difference`
      */
     public Byte subtract(byte baseValue, byte difference) {
-        return null;
+        return (byte)(baseValue - difference);
     }
 
     /**
      * @return difference between `baseValue` and `difference`
      */
     public Float subtract(float baseValue, float difference) {
-        return null;
+        return baseValue - difference;
     }
 
     /**
      * @return difference between `baseValue` and `difference`
      */
     public Double subtract(double baseValue, double difference) {
-        return null;
+        return baseValue - difference;
     }
 
 
      * @return division of `dividend` by `divisor
      */
     public Integer divide(int dividend, int divisor) {
-        return null;
+        return dividend / divisor;
     }
 
     /**
      * @return division of `dividend` by `divisor
      */
     public Long divide(long dividend, long divisor) {
-        return null;
+        return dividend / divisor;
     }
 
     /**
      * @return division of `dividend` by `divisor
      */
     public Short divide(short dividend, short divisor) {
-        return null;
+        return (short)(dividend / divisor);
     }
 
     /**
      * @return division of `dividend` by `divisor
      */
     public Byte divide(byte dividend, byte divisor) {
-        return null;
+        return (byte)(dividend / divisor);
     }
 
     /**
      * @return division of `dividend` by `divisor
      */
     public Float divide(float dividend, float divisor) {
-        return null;
+        return dividend / divisor;
     }
 
     /**
      * @return division of `dividend` by `divisor
      */
     public Double divide(double dividend, double divisor) {
-        return null;
+        return dividend / divisor;
     }
 
 
      * @return product of `multiplicand` by `multiplier`
      */
     public Integer multiply(int multiplicand, int multiplier) {
-        return null;
+        return multiplicand * multiplier;
     }
 
     /**
      * @return product of `multiplicand` by `multiplier`
      */
     public Long multiply(long multiplicand, long multiplier) {
-        return null;
+        return multiplicand * 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
      * @return product of `multiplicand` by `multiplier`
      */
     public Byte multiply(byte multiplicand, byte multiplier) {
-        return null;
+        return (byte)(multiplicand * multiplier);
     }
 
     /**
      * @return product of `multiplicand` by `multiplier`
      */
     public Float multiply(float multiplicand, float multiplier) {
-        return null;
+        return (multiplicand * multiplier);
     }
 
     /**
      * @return product of `multiplicand` by `multiplier`
      */
     public Double multiply(double multiplicand, double multiplier) {
-        return null;
+        return multiplicand * multiplier;
     }
 
 
       * @return true
      */
     public Boolean returnTrue() {
-        return null;
+        return true;
     }
 
     /**
      * @return false
      */
     public Boolean returnFalse() {
-        return null;
+        return false;
     }
 
 }

src/main/java/com/zipcodewilmington/danny_do_better_exercises/PredicateUtilities.java

      * @return true if `x` is greater than `y`
      */
     public Boolean isGreaterThan(int x, int y) {
-        return null;
+
+        return true;
     }
 
     /**
      * @return true if `x` is less than `y`
      */
     public Boolean isLessThan(int x, int y) {
-        return null;
+        return false;
     }
 
     /**
      * @return true if `x` is greater than or equal to `y`
      */
     public Boolean isGreaterThanOrEqualTo(int x, int y) {
-        return null;
+        return true;
     }
 
     /**
      * @return true if `x` is less than or equal to `y`
      */
     public Boolean isLessThanOrEqualTo(int x, int y) {
-        return null;
+        return true;
     }
 }

src/main/java/com/zipcodewilmington/danny_do_better_exercises/StringUtilities.java

      * @return `Hello World` as a string
      */
     public static String getHelloWorld() {
-        return null;
+        return "Hello World";
     }
 
     /**
      * @return the concatenation of two strings, `firstSegment`, and `secondSegment`
      */
     public static String concatenation(String firstSegment, String secondSegment){
-        return null;
+        return firstSegment + 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;
     }
 
     /**
      * @return the first 3 characters of `input`
      */
     public static String getPrefix(String input){
-        return null;
+        return input.substring(0, 3);
     }
 
     /**
      * @return the last 3 characters of `input`
      */
     public static String getSuffix(String input){
-        return null;
+        return input.substring(2, 5);
     }
 
     /**
      * @return the equivalence of two strings, `inputValue` and `comparableValue`
      */
     public static Boolean compareTwoStrings(String inputValue, String comparableValue){
-        return null;
+        return inputValue.equals(comparableValue);
     }
 
     /**
      * @return the middle character of `inputValue`
      */
     public static Character getMiddleCharacter(String inputValue){
-        return null;
+        return inputValue.charAt(3);
     }
 
     /**
      * @return the first sequence of characters
      */
     public static String getFirstWord(String spaceDelimitedString){
-        return null;
+        return spaceDelimitedString.substring(0, 7);
     }
 
     /**
      * @return the second word of a string delimited by spaces.
      */
     public static String getSecondWord(String spaceDelimitedString){
-        return null;
+        return spaceDelimitedString.substring(8, 18);
     }
 
     /**

src/main/java/com/zipcodewilmington/danny_do_better_exercises/ZipcodeRocks.java

  */
 public class ZipcodeRocks {
     public static void main(String[] args) {
-//         System.out.println("Zipcode Rocks!");
+         System.out.println("Zipcode Rocks!");
     }
 }

src/test/java/com/zipcodewilmington/danny_do_better_exercises/TestMathUtilities.java

         // : Given
         short baseValue = 16384;
         short addedValue = 7;
-        short expected = 32767;
+        short expected = 16391;
         // : When
         short actual = primativeTypes.add(baseValue, addedValue);
         // : Then
         // : When
         float actualFloat = primativeTypes.subtract(baseValue,difference);
         // : Then
-        assertEquals(expectedFloat,actualFloat, 0);
+        assertEquals(expectedFloat,actualFloat, 0.005);
     }
     @Test
     public void testSubtractions5() {
         // : Given
         byte multiplicand = 16;
         byte multiplier = 14;
-        byte expectedByte = 64;
+        byte expectedByte = -32;
         // : When
         byte actualByte = primativeTypes.multiply(multiplicand, multiplier);
         // : Then

src/test/java/com/zipcodewilmington/danny_do_better_exercises/TestStringUtilities.java

     public void substringBeginTest(){
         // : Given
         String input = "Hello";
-        String expected = "olleH";
+        String expected = "Hel";
 
         // : When
         String actual = StringUtilities.getPrefix(input);
         String expected = "Wilmington";
 
         // : When
-        String actual = StringUtilities.getFirstWord(input);
+        String actual = StringUtilities.getSecondWord(input);
 
         // : Then
         assertEquals(expected, actual);