diff --git a/lesson8/13_add_type_parameters.go b/lesson8/13_add_type_parameters.go
new file mode 100644
index 0000000..a9012ef
--- /dev/null
+++ b/lesson8/13_add_type_parameters.go
@@ -0,0 +1,29 @@
+// Again - no automatic type conversion is performed!
+
+package main
+
+import "fmt"
+
+type numeric interface {
+	int | float64 | complex128
+}
+
+func add[T numeric](x T, y T) T {
+	return x + y
+}
+
+type myInt int
+
+type myFloat float64
+
+type myComplex complex128
+
+func main() {
+	var x myInt = 42
+	var y myFloat = 3.14
+	var z myComplex = 1 + 2i
+
+	fmt.Println(add(x, x))
+	fmt.Println(add(y, y))
+	fmt.Println(add(z, z))
+}