diff --git a/ch_02/hex_converter/main.c b/ch_02/hex_converter/main.c
new file mode 100644
index 0000000..28c97c7
--- /dev/null
+++ b/ch_02/hex_converter/main.c
@@ -0,0 +1,344 @@
+/*
+ *
+ * Write a program that can convert a decimal to a hex value and vice-versa.
+ * The program must pass a command line argument to determine what will
+ * be the conversion type and the value to be converted. The value
+ * must be evaluated to make sure it's valid before converting.
+ * Otherwise, inform the user and terminate the program
+ *
+ * Author: Kun Deng
+ */
+
+
+
+#include <stdio.h>
+#include <stdlib.h>
+
+// Symbolic constants
+#define INVALID 0
+#define HEX 1
+#define NUMBER 2
+
+
+char hex_value[15];
+
+// Return values
+// 0 - Invalid
+// 1 - Converting to hex
+// 2 - Converting to number
+int is_valid_conversion_target(char *target);
+
+// Parameter target_type is the valid target type
+// Should match the symbolic constants of HEX or NUMBER
+//
+// Return values
+// 0 - Invalid
+// 1 - Valid
+int is_valid_source(char *value, int target_type);
+
+// Returns the size of the string. Assumes that the value is a null terminated string
+int size_of_string(char *value);
+
+// Compares two strings. Assumes that the strings are null terminated
+// Return values
+// 0 - Not equal
+// 1 - Equal
+int compare_string(char *first, char *second);
+
+// Converts the hex value to a number
+int hex_conveted_to_number(char *value);
+
+
+// Converts the number to a hex value
+char* number_converted_to_hex(char *value);
+
+
+// Converts a digit to it's Hex counterpart.
+// Ex. 15 would be F
+char convert_hex_part(int val);
+
+
+// Reverses the order of a null terminated string
+void reverse_order(char *val);
+
+
+int main(int argc, char **argv)
+{
+    if (argc < 3)
+    {
+        printf("Provide two arguments:\n");
+        printf("./program [conversion_target] [decimal | hex value]\n");
+        printf("[conversion_target] - hex or dec as the target\n");
+        printf("hex - converts the decimal value to hex\n");
+        printf("dec - converts the hex value to decimal\n");
+
+        return -1;
+    }
+
+    char *conversion_target = *(argv + 1);
+
+    printf("Chose conversion target %s\n", conversion_target);
+
+    int valid_target = is_valid_conversion_target(conversion_target);
+    char *val = *(argv + 2);
+
+    switch (valid_target)
+    {
+        case HEX:
+            printf("%s is a valid conversion target\n", conversion_target);
+
+            if (is_valid_source(val, HEX) != 1)
+            {
+                printf("%s is not a valid number\n", val);
+
+                return -1;
+            }
+
+            char *converted_to_hex = number_converted_to_hex(val);
+
+            printf("%s converted to hex is %s\n", val, converted_to_hex);
+            break;
+        case NUMBER:
+            printf("%s is a valid conversion target\n", conversion_target);
+
+            if (is_valid_source(val, NUMBER) != 1)
+            {
+                printf("%s is not a valid hex number\n", val);
+            }
+            break;
+        case INVALID:
+            printf("%s is an invalid conversion target\n", conversion_target);
+            break;
+        default:
+            break;
+    }
+
+
+    return 0;
+}
+
+
+
+int is_valid_conversion_target(char *target)
+{
+    int result = 0;
+
+    if (compare_string(target, "hex") == 1)
+    {
+        result = 1;
+    }
+    else if (compare_string(target, "num") == 1)
+    {
+        result = 2;
+    }
+
+
+    return result;
+}
+
+int is_valid_source(char *value, int target_type)
+{
+    int result = 1;
+
+    for (int i = 0; value[i] != '\0'; ++i)
+    {
+        char val = value[i];
+
+        if (target_type == NUMBER)
+        {
+            // ASCI values
+            // 48 - 57 are numbers
+            // 65 - 70 are upper case letters (A-F)
+            // 97 - 102 are lower case letters (a-f)
+            if (!(val >= 48 && val <= 57) && 
+                    !(val >= 65 && val <= 70) &&
+                    !(val >= 97 && val <= 102))
+            {
+                result = 0;
+                break;
+            }
+        }
+        else if (target_type == HEX)
+        {
+            // ASCII values 48 - 57 are numbers
+            // Checks to see if there are non-numbers
+            if (val <= 47 || val >= 58)
+            {
+                result = 0;
+                break;
+            }
+        }
+    }
+
+    return result;
+}
+
+int size_of_string(char *value)
+{
+    int size = 0;
+
+    while (value[size] != '\0')
+    {
+        ++size;
+    }
+
+    return size;
+}
+
+int compare_string(char *first, char *second)
+{
+    int result = 1;
+    int size_first, size_second;
+
+    size_first = size_of_string(first);
+    size_second = size_of_string(second);
+
+    if (size_first != size_second)
+    {
+        return --result;
+    }
+
+    for (int i = 0; i != size_first; ++i)
+    {
+        if (first[i] != second[i])
+        {
+            result = 0;
+            break;
+        }
+    }
+
+
+    return result;
+}
+
+int hex_conveted_to_number(char *value)
+{
+    int number = 0;
+
+    return number;
+}
+
+
+char *number_converted_to_hex(char *value)
+{
+    int number_value = atoi(value);
+    int string_size = size_of_string(value);
+
+    extern char hex_value[];
+
+    int hex_start = 0;
+
+    for (double number = number_value;;)
+    {
+        double quotient = number / 16.0;
+        int quotient_trunecated = number / 16;
+        double remaining = quotient - quotient_trunecated;
+        int number_hex_part = remaining * 16;
+
+        if (number >= 16)
+        {
+            char hex_part = convert_hex_part(number_hex_part);
+            printf("Hex part %c\n", hex_part);
+
+            hex_value[hex_start++] = hex_part;
+        }
+        else
+        {
+            char hex_part = convert_hex_part(number_hex_part);
+            printf("Last Hex part %c\n", hex_part);
+
+            hex_value[hex_start++] = hex_part;
+            break;
+        }
+
+        number = quotient_trunecated;
+    }
+
+    hex_value[hex_start] = '\0';
+
+    if (hex_start > 1)
+    {
+        reverse_order(hex_value);
+    }
+
+    /**
+    for (int i = (string_size - 1); i >= 0; --i)
+    {
+        int number_part = value[i] - '0';
+
+        printf("Number part %d\n", number_part);
+
+
+        ++hex_start;
+    }
+    */
+
+
+    return hex_value;
+}
+
+
+char convert_hex_part(int val)
+{
+    char result;
+
+    if (val == 15)
+    {
+        result = 'F';
+    }
+    else if (val == 14)
+    {
+        result = 'E';
+    }
+    else if (val == 13)
+    {
+        result = 'D';
+    }
+    else if (val == 12)
+    {
+        result = 'C';
+    }
+    else if (val == 11)
+    {
+        result = 'B';
+    }
+    else if (val == 10)
+    {
+        result = 'A';
+    }
+    else
+    {
+        result = val + '0';
+    }
+
+    return result;
+}
+
+
+void reverse_order(char *value)
+{
+    int string_size = size_of_string(value);
+
+    printf("Before %s", value);
+
+    for (int i = 0;; ++i)
+    {
+        char tmp = value[string_size - i - 1];
+        value[string_size - i - 1] = value[i];
+        value[i] = tmp;
+
+        // 1 if odd, 0 if true
+        int is_odd = string_size % 2;
+
+        if (is_odd == 1 && (string_size / 2) == ((i + 1)))
+        {
+            break;
+        }
+        else if (is_odd == 0 && (string_size / 2) == (i + 1))
+        {
+            break;
+        }
+    }
+
+    printf(" After %s\n", value);
+}
diff --git a/ch_02/hex_converter/main_template.c b/ch_02/hex_converter/main_template.c
deleted file mode 100644
index d432873..0000000
--- a/ch_02/hex_converter/main_template.c
+++ /dev/null
@@ -1,10 +0,0 @@
-/*
- *
- * Write a program that can convert a decimal to a hex value and vice-versa.
- * The program must pass a command line argument to determine what will
- * be the conversion type and the value to be converted. The value
- * must be evaluated to make sure it's valid before converting.
- * Otherwise, inform the user and terminate the program
- *
- * Author: Kun Deng
- */
diff --git a/ch_02/octal_converter/README.md b/ch_02/octal_converter/README.md
new file mode 100644
index 0000000..15f93da
--- /dev/null
+++ b/ch_02/octal_converter/README.md
@@ -0,0 +1,2 @@
+compile with math library using gcc:
+gcc main.c -lm
diff --git a/ch_02/octal_converter/main.c b/ch_02/octal_converter/main.c
index 3883041..332d8a5 100644
--- a/ch_02/octal_converter/main.c
+++ b/ch_02/octal_converter/main.c
@@ -1,6 +1,6 @@
 /*
  *
- * Write a program that can convert a decimal to a hex value and vice-versa.
+ * Write a program that can convert a number to a hex value and vice-versa.
  * The program must pass a command line argument to determine what will
  * be the conversion type and the value to be converted. The value
  * must be evaluated to make sure it's valid before converting.
@@ -14,16 +14,16 @@
 #include <math.h>
 
 #define OCTAL 1
-#define DECIMAL 2
+#define NUMBER 2
 
 
 // Returns 1 if octal conversion was chosen
-// Returns 2 if decimal conversion was chosen
+// Returns 2 if number conversion was chosen
 // Returns 0 or non-zero number if not valid
-int valid_conversion_option(char *option);
+int valid_conversion_target(char *target);
 
-// Returns 1 if valid and 0 if the decimal value isn't
-int valid_decimal_value(char *value);
+// Returns 1 if valid and 0 if the number value isn't
+int valid_number_value(char *value);
 
 // Returns 1 if valid and 0 if the octal value isn't
 int valid_octal_value(char *value);
@@ -33,41 +33,45 @@ int valid_octal_value(char *value);
 int size_of_value(char *value);
 
 
-// Converts decimal value to octal and prints the value
+// Converts number value to octal and prints the value
 void convert_to_octal(char *value);
 
-// Converts octal value to decimal and prints the value
-void convert_to_decimal(char *value);
+// Converts octal value to number and prints the value
+void convert_to_number(char *value);
 
 
 int main(int argc, char **argv)
 {
     if (argc < 3)
     {
-        printf("Provide two arguments: ./program [conversion_option] [decimal | octal value]\n");
+        printf("Provide two arguments:\n");
+        printf("./program [conversion_target] [number | octal value]\n");
+        printf("[conversion_target] - oct or num as the target\n");
+        printf("oct - Converts the number to a hex value\n");
+        printf("num - Converts the octal value to a number\n");
 
         return -1;
     }
 
 
-    char *conversion_option = argv[1];
-    int result = valid_conversion_option(conversion_option);
+    char *conversion_target = argv[1];
+    int result = valid_conversion_target(conversion_target);
 
     if (result < 1)
     {
-        printf("Invalid conversion option %s.\noct and dec are only supported\n", conversion_option);
+        printf("Invalid conversion target %s.\noct and num are only supported\n", conversion_target);
 
         return -1;
     }
 
-    printf("%s is a valid conversion option\n", conversion_option);
+    printf("%s is a valid conversion target\n", conversion_target);
 
     switch (result)
     {
         case OCTAL:
-            if (valid_decimal_value(argv[2]) == 0)
+            if (valid_number_value(argv[2]) == 0)
             {
-                printf ("Invalid decimal value %s\n", argv[2]);
+                printf ("Invalid number value %s\n", argv[2]);
 
                 return -1;
             }
@@ -75,7 +79,7 @@ int main(int argc, char **argv)
             convert_to_octal(argv[2]);
 
             break;
-        case DECIMAL:
+        case NUMBER:
             if (valid_octal_value(argv[2]) == 0)
             {
                 printf("Invalid octal value %s\n", argv[2]);
@@ -83,7 +87,7 @@ int main(int argc, char **argv)
                 return -1;
             }
 
-            convert_to_decimal(argv[2]);
+            convert_to_number(argv[2]);
 
             break;
     }
@@ -93,12 +97,12 @@ int main(int argc, char **argv)
 }
 
 
-int valid_conversion_option(char *option)
+int valid_conversion_target(char *target)
 {
     const int OPTION_SIZE = 4;
-    // Supported conversion options
+    // Supported conversion targets
     char *oct = "oct";
-    char *dec = "dec";
+    char *num = "num";
     
 
     int result = 0;
@@ -106,7 +110,7 @@ int valid_conversion_option(char *option)
     for (int a = 0; a != OPTION_SIZE; ++a)
     {
         // Checking to see if octal conversion is selected
-        if (option[a] != oct[a])
+        if (target[a] != oct[a])
         {
             break;
         }
@@ -119,8 +123,8 @@ int valid_conversion_option(char *option)
 
     for (int a = 0; a != OPTION_SIZE; ++a)
     {
-        // Checking to see if decimal conversion is selected
-        if (option[a] != dec[a])
+        // Checking to see if number conversion is selected
+        if (target[a] != num[a])
         {
             break;
         }
@@ -135,7 +139,7 @@ int valid_conversion_option(char *option)
     return result;
 }
 
-int valid_decimal_value(char *value)
+int valid_number_value(char *value)
 {
     int result = 1;
 
@@ -143,11 +147,11 @@ int valid_decimal_value(char *value)
     {
         // ASCII value 48 is 0. ASCII value 57 is 9.
         // If value contains any non-numbers then
-        // the value isn't a valid decimal value
+        // the value isn't a valid number value
         if (value[a] < 48 || value[a] > 57)
         {
             result = 0;
-            printf("Invalid character for decimal %c\n", value[a]);
+            printf("Invalid character for number %c\n", value[a]);
 
             break;
         }
@@ -190,31 +194,31 @@ int size_of_value(char *value)
 
 void convert_to_octal(char *value)
 {
-    int value_decimal = atoi(value);
+    int value_number = atoi(value);
     char octal_value[12] = "00000000000\0";
     int index = 0;
 
-    printf("Converting %d to octal\n", value_decimal);
+    printf("Converting %d to octal\n", value_number);
 
-   for (double quotient_decimal = value_decimal; (quotient_decimal >= 0);)
+   for (double quotient_number = value_number; (quotient_number >= 0);)
     {
-        if (quotient_decimal == 0)
+        if (quotient_number == 0)
         {
             octal_value[index] = '0';
             break;
         }
         else
         {
-            quotient_decimal /= 8;
-            int trunecated_quotient_decimal = quotient_decimal;
-            double remaining = quotient_decimal - trunecated_quotient_decimal;
+            quotient_number /= 8;
+            int trunecated_quotient_number = quotient_number;
+            double remaining = quotient_number - trunecated_quotient_number;
             int octal_part = remaining * 8;
 
-            printf("Octal part %d index %d remaining %f\n", octal_part, index, quotient_decimal);
+            printf("Octal part %d index %d remaining %f\n", octal_part, index, quotient_number);
 
             octal_value[index] = octal_part + '0';
 
-            quotient_decimal = trunecated_quotient_decimal;
+            quotient_number = trunecated_quotient_number;
 
             ++index;
         }
@@ -231,24 +235,24 @@ void convert_to_octal(char *value)
    }
 
 
-    printf("Decimal value %d is %s in octal\n", value_decimal, octal_value);
+    printf("Decimal value %d is %s in octal\n", value_number, octal_value);
 }
 
-void convert_to_decimal(char *value)
+void convert_to_number(char *value)
 {
-    int octal_converted_to_decimal = 0;
+    int octal_converted_to_number = 0;
     int power_value = 0;
 
-    printf("Converting %s to decimal\n", value);
+    printf("Converting %s to number\n", value);
 
     for (int a = size_of_value(value) - 1; a >= 0; --a)
     {
         int octal_part = value[a] - '0';
         int octal_power = octal_part * pow(8, power_value++);
-        octal_converted_to_decimal += octal_power;
+        octal_converted_to_number += octal_power;
 
         printf("Octal part %d octal power %d\n", octal_part, octal_power);
     }
 
-    printf("Octal value %s is %d in decimal\n", value, octal_converted_to_decimal);
+    printf("Octal value %s is %d in number\n", value, octal_converted_to_number);
 }
diff --git a/ch_02/octal_converter/main_template.c b/ch_02/octal_converter/main_template.c
deleted file mode 100644
index d432873..0000000
--- a/ch_02/octal_converter/main_template.c
+++ /dev/null
@@ -1,10 +0,0 @@
-/*
- *
- * Write a program that can convert a decimal to a hex value and vice-versa.
- * The program must pass a command line argument to determine what will
- * be the conversion type and the value to be converted. The value
- * must be evaluated to make sure it's valid before converting.
- * Otherwise, inform the user and terminate the program
- *
- * Author: Kun Deng
- */