diff --git a/20201119/main.go b/20201119/main.go
new file mode 100644
index 0000000..84c00da
--- /dev/null
+++ b/20201119/main.go
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	fmt.Println(multiple(9, 9))
+}
+
+func multiple(n, m uint64) uint64 {
+	if m == 1 {
+		return n
+	}
+	return n + multiple(n, m-1)
+}
+
+func multiple2(n, m uint64) uint64 {
+	sum := n
+	m--
+	if m > 0 {
+		sum += multiple2(n, m)
+	}
+	return sum
+}
diff --git a/20201119/main_test.go b/20201119/main_test.go
new file mode 100644
index 0000000..a1221e4
--- /dev/null
+++ b/20201119/main_test.go
@@ -0,0 +1,83 @@
+package main
+
+import "testing"
+
+func Test_multiple(t *testing.T) {
+	type args struct {
+		n uint64
+		m uint64
+	}
+	tests := []struct {
+		name string
+		args args
+		want uint64
+	}{
+		{
+			"example_1",
+			args{1, 10},
+			10,
+		},
+		{
+			"example_2",
+			args{3, 4},
+			12,
+		},
+		{
+			"example_3",
+			args{100, 100},
+			10000,
+		},
+		{
+			"example_4",
+			args{300, 100},
+			30000,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := multiple(tt.args.n, tt.args.m); got != tt.want {
+				t.Errorf("multiple() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_multiple2(t *testing.T) {
+	type args struct {
+		n uint64
+		m uint64
+	}
+	tests := []struct {
+		name string
+		args args
+		want uint64
+	}{
+		{
+			"example_1",
+			args{1, 10},
+			10,
+		},
+		{
+			"example_2",
+			args{3, 4},
+			12,
+		},
+		{
+			"example_3",
+			args{100, 100},
+			10000,
+		},
+		{
+			"example_4",
+			args{300, 100},
+			30000,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := multiple2(tt.args.n, tt.args.m); got != tt.want {
+				t.Errorf("multiple2() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}