diff --git a/chapter_05/activity_5.02/main.go b/chapter_05/activity_5.02/main.go
new file mode 100644
index 0000000..db141ec
--- /dev/null
+++ b/chapter_05/activity_5.02/main.go
@@ -0,0 +1,116 @@
+package main
+
+import "fmt"
+
+type Employee struct {
+  Id        int
+  FirstName string
+  LastName  string
+}
+
+type Developer struct {
+  Individual Employee
+  HourlyRate int
+  WorkWeek   [7]int
+}
+
+type Weekday int
+
+const (
+  Sunday Weekday = iota
+  Monday
+  Tuesday
+  Wednesday
+  Thursday
+  Friday
+  Saturday
+)
+
+func main() {
+
+  d := Developer{Individual: Employee{Id: 1, FirstName: "Tony", LastName: "Stark"}, HourlyRate: 10}
+
+  x := nonLoggedHours()
+
+  fmt.Println("Tracking hours worked so far today:", x(2))
+  fmt.Println("Tracking hours worked so far today:", x(3))
+  fmt.Println("Tracking hours worked so far today:", x(5))
+
+  d.LogHours(Monday, 8)
+  d.LogHours(Tuesday, 10)
+  d.LogHours(Wednesday, 10)
+  d.LogHours(Thursday, 10)
+  d.LogHours(Friday, 6)
+  d.LogHours(Saturday, 8)
+
+  d.PayDetails()
+
+}
+
+func (d *Developer) LogHours(day Weekday, hours int) {
+
+  d.WorkWeek[day] = hours
+
+}
+
+func (d *Developer) HoursWorked() int {
+
+  total := 0
+  for _, v := range d.WorkWeek {
+    total += v
+  }
+  return total
+
+}
+
+func (d *Developer) PayDay() (int, bool) {
+
+  if d.HoursWorked() > 40 {
+    hoursOver := d.HoursWorked() - 40
+    overTime := hoursOver * 2 * d.HourlyRate
+    regularPay := 40 * d.HourlyRate
+    return regularPay + overTime, true
+  }
+
+  return d.HoursWorked() * d.HourlyRate, false
+
+}
+
+func nonLoggedHours() func(int) int {
+
+  total := 0
+
+  return func(i int) int {
+    total += i
+    return total
+  }
+
+}
+
+func (d *Developer) PayDetails() {
+
+  for i, v := range d.WorkWeek {
+    switch i {
+    case 0:
+      fmt.Println("Sunday hours:", v)
+    case 1:
+      fmt.Println("Monday hours:", v)
+    case 2:
+      fmt.Println("Tuesday hours:", v)
+    case 3:
+      fmt.Println("Wednesday hours:", v)
+    case 4:
+      fmt.Println("Thursday hours:", v)
+    case 5:
+      fmt.Println("Friday hours:", v)
+    case 6:
+      fmt.Println("Saturday hours:", v)
+    }
+  }
+
+  fmt.Println("Hours worked this week:", d.HoursWorked())
+  pay, over := d.PayDay()
+  fmt.Println("Pay for the week:", pay)
+  fmt.Println("Is this overtime pay:", over)
+
+}
diff --git a/chapter_05/exercise_5.04/main.go b/chapter_05/exercise_5.04/main.go
new file mode 100644
index 0000000..a6a2bcd
--- /dev/null
+++ b/chapter_05/exercise_5.04/main.go
@@ -0,0 +1,40 @@
+package main
+
+import (
+  "fmt"
+  "strings"
+)
+
+func main() {
+
+  hdr := []string{"empid", "employee", "address", "hours worked",
+    "hourly rate", "manager"}
+  result := csvHdrCol(hdr)
+  fmt.Println("Result:")
+  fmt.Println(result)
+  fmt.Println()
+
+  hdr2 := []string{"employee", "empid", "hours worked", "address",
+    "manager", "hourly rate"}
+  result2 := csvHdrCol(hdr2)
+  fmt.Println("Result2:")
+  fmt.Println(result2)
+  fmt.Println()
+
+}
+
+func csvHdrCol(hdr []string) map[int]string {
+
+  csvIdxToCol := make(map[int]string)
+
+  for i, v := range hdr {
+    v = strings.TrimSpace(v)
+    switch strings.ToLower(v) {
+    case "employee", "hours worked", "hourly rate":
+      csvIdxToCol[i] = v
+    }
+  }
+
+  return csvIdxToCol
+
+}
diff --git a/chapter_05/exercise_5.05/main.go b/chapter_05/exercise_5.05/main.go
new file mode 100644
index 0000000..328c9fd
--- /dev/null
+++ b/chapter_05/exercise_5.05/main.go
@@ -0,0 +1,23 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  i := []int{5, 10, 15}
+  fmt.Println(sum(5, 4))
+  fmt.Println(sum(i...))
+
+}
+
+func sum(nums ...int) int {
+
+  total := 0
+
+  for _, num := range nums {
+    total += num
+  }
+
+  return total
+
+}
diff --git a/chapter_05/exercise_5.06/main.go b/chapter_05/exercise_5.06/main.go
new file mode 100644
index 0000000..651bc72
--- /dev/null
+++ b/chapter_05/exercise_5.06/main.go
@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  j := 9
+
+  x := func(i int) int {
+    return i * i
+  }
+
+  fmt.Printf("The square of %d is %d\n", j, x(j))
+  fmt.Printf("The square of %d is %d\n", j, func(i int) int { return i * i }(j))
+
+}
diff --git a/chapter_05/exercise_5.07/main.go b/chapter_05/exercise_5.07/main.go
new file mode 100644
index 0000000..b781065
--- /dev/null
+++ b/chapter_05/exercise_5.07/main.go
@@ -0,0 +1,26 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  counter := 4
+
+  x := decrement(counter)
+  fmt.Println(x())
+  fmt.Println(x())
+  fmt.Println(x())
+  fmt.Println(x())
+
+  fmt.Println("counter:", counter)
+
+}
+
+func decrement(i int) func() int {
+
+  return func() int {
+    i--
+    return i
+  }
+
+}
diff --git a/chapter_05/exercise_5.08/main.go b/chapter_05/exercise_5.08/main.go
new file mode 100644
index 0000000..ba59ddc
--- /dev/null
+++ b/chapter_05/exercise_5.08/main.go
@@ -0,0 +1,32 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  devSalary := salary(50, 2080, developerSalary)
+  bossSalary := salary(150000, 25000, managerSalary)
+
+  fmt.Printf("Boss salary: %d\n", bossSalary)
+  fmt.Printf("Developer salary: %d\n", devSalary)
+
+}
+
+func salary(x, y int, f func(int, int) int) int {
+
+  pay := f(x, y)
+  return pay
+
+}
+
+func developerSalary(hourlyRate, hoursWorked int) int {
+
+  return hourlyRate * hoursWorked
+
+}
+
+func managerSalary(baseSalary, bonus int) int {
+
+  return baseSalary + bonus
+
+}