diff --git a/chapter_04/activity_4.01/main.go b/chapter_04/activity_4.01/main.go
new file mode 100644
index 0000000..afb10ef
--- /dev/null
+++ b/chapter_04/activity_4.01/main.go
@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+func main() {
+
+  var arr [10]int
+
+  for i := 0; i < len(arr); i++ {
+    arr[i] = i + 1
+  }
+
+  fmt.Println(arr)
+
+}
diff --git a/chapter_04/exercise_4.01/main.go b/chapter_04/exercise_4.01/main.go
new file mode 100644
index 0000000..c957801
--- /dev/null
+++ b/chapter_04/exercise_4.01/main.go
@@ -0,0 +1,21 @@
+package main
+
+import "fmt"
+
+func defineArray() [10]int {
+
+  var arr [10]int
+  return arr
+
+}
+
+func main() {
+
+  fmt.Printf("%#v\n", defineArray())
+
+  // Array with size set from initialization
+  // []int would be result in a slice
+  bla := [...]int{1, 2, 3, 4, 5}
+  fmt.Printf("%#v\n", bla)
+
+}
diff --git a/chapter_04/exercise_4.02/main.go b/chapter_04/exercise_4.02/main.go
new file mode 100644
index 0000000..272230a
--- /dev/null
+++ b/chapter_04/exercise_4.02/main.go
@@ -0,0 +1,23 @@
+package main
+
+import "fmt"
+
+func compArrays() (bool, bool, bool) {
+
+  var arr1 [5]int
+  arr2 := [5]int{0}
+  arr3 := [...]int{0, 0, 0, 0, 0}
+  arr4 := [5]int{0, 0, 0, 0, 9}
+
+  return arr1 == arr2, arr1 == arr3, arr1 == arr4
+}
+
+func main() {
+
+  comp1, comp2, comp3 := compArrays()
+
+  fmt.Println("[5]int == [5]int{0}              :", comp1)
+  fmt.Println("[5]int == [...]int{0, 0, 0, 0, 0}:", comp2)
+  fmt.Println("[5]int == [5]int{0, 0, 0, 0, 9}  :", comp3)
+
+}
diff --git a/chapter_04/exercise_4.03/main.go b/chapter_04/exercise_4.03/main.go
new file mode 100644
index 0000000..46a04fe
--- /dev/null
+++ b/chapter_04/exercise_4.03/main.go
@@ -0,0 +1,22 @@
+package main
+
+import "fmt"
+
+func compArrays() (bool, bool, [10]int) {
+
+  var arr1 [10]int
+  arr2 := [...]int{9: 0}
+  arr3 := [10]int{1, 9: 10, 4: 5}
+
+  return arr1 == arr2, arr1 == arr3, arr3
+}
+
+func main() {
+
+  comp1, comp2, arr3 := compArrays()
+
+  fmt.Println("[10]int == [...]int{9: 0}         :", comp1)
+  fmt.Println("[10]int == [10]int{1, 9: 10, 4: 5}:", comp2)
+  fmt.Println("arr3                              :", arr3)
+
+}
diff --git a/chapter_04/exercise_4.04/main.go b/chapter_04/exercise_4.04/main.go
new file mode 100644
index 0000000..0eef57e
--- /dev/null
+++ b/chapter_04/exercise_4.04/main.go
@@ -0,0 +1,22 @@
+package main
+
+import "fmt"
+
+func message() string {
+
+  arr := [...]string{
+    "ready",
+    "Get",
+    "Go",
+    "to",
+  }
+
+  return fmt.Sprintln(arr[1], arr[0], arr[3], arr[2])
+
+}
+
+func main() {
+
+  fmt.Print(message())
+
+}
diff --git a/chapter_04/exercise_4.05/main.go b/chapter_04/exercise_4.05/main.go
new file mode 100644
index 0000000..7ffed66
--- /dev/null
+++ b/chapter_04/exercise_4.05/main.go
@@ -0,0 +1,20 @@
+package main
+
+import "fmt"
+
+func message() string {
+
+  arr := [4]string{"ready", "Get", "Go", "to"}
+
+  arr[1] = "It's"
+  arr[0] = "time"
+
+  return fmt.Sprintln(arr[1], arr[0], arr[3], arr[2])
+
+}
+
+func main() {
+
+  fmt.Print(message())
+
+}
diff --git a/chapter_04/exercise_4.06/main.go b/chapter_04/exercise_4.06/main.go
new file mode 100644
index 0000000..7ed13ce
--- /dev/null
+++ b/chapter_04/exercise_4.06/main.go
@@ -0,0 +1,23 @@
+package main
+
+import "fmt"
+
+func message() string {
+
+  m := ""
+  arr := [4]int{1, 2, 3, 4}
+
+  for i := 0; i < len(arr); i++ {
+    arr[i] *= arr[i]
+    m += fmt.Sprintf("%v: %v\n", i, arr[i])
+  }
+
+  return m
+
+}
+
+func main() {
+
+  fmt.Print(message())
+
+}
diff --git a/chapter_04/exercise_4.07/main.go b/chapter_04/exercise_4.07/main.go
new file mode 100644
index 0000000..6a2cfcc
--- /dev/null
+++ b/chapter_04/exercise_4.07/main.go
@@ -0,0 +1,32 @@
+package main
+
+import "fmt"
+
+func fillArray(arr [10]int) [10]int {
+
+  for i := 0; i < len(arr); i++ {
+    arr[i] = i + 1
+  }
+
+  return arr
+
+}
+
+func opArray(arr [10]int) [10]int {
+
+  for i := 0; i < len(arr); i++ {
+    arr[i] *= arr[i]
+  }
+
+  return arr
+
+}
+
+func main() {
+
+  var arr [10]int
+  arr = fillArray(arr)
+  arr = opArray(arr)
+  fmt.Println(arr)
+
+}