diff --git a/20201110_find_lost_number/main.go b/20201110_find_lost_number/main.go
index 0988795..1cf32ae 100644
--- a/20201110_find_lost_number/main.go
+++ b/20201110_find_lost_number/main.go
@@ -24,8 +24,8 @@ func findLostNumber(nums []int) int {
 	for _, n := range nums {
 		sum += n
 	}
-	n := len(nums)
-	return n*(n+1)/2 - sum
+	l := len(nums)
+	return l*(l+1)/2 - sum
 }
 
 func findLostNumber2(nums []int) int {
diff --git a/20201110_find_lost_number/main_test.go b/20201110_find_lost_number/main_test.go
index 9337bd1..30d21e6 100644
--- a/20201110_find_lost_number/main_test.go
+++ b/20201110_find_lost_number/main_test.go
@@ -23,6 +23,16 @@ func Test_findLostNumber(t *testing.T) {
 			args{[]int{9, 6, 4, 2, 3, 5, 7, 0, 1}},
 			8,
 		},
+		{
+			"example_3",
+			args{[]int{8, 6, 4, 2, 3, 5, 7, 0, 1}},
+			9,
+		},
+		{
+			"example_4",
+			args{[]int{9, 8, 6, 4, 2, 3, 5, 7, 1}},
+			0,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -52,6 +62,11 @@ func Test_findLostNumber2(t *testing.T) {
 			args{[]int{9, 6, 4, 2, 3, 5, 7, 0, 1}},
 			8,
 		},
+		{
+			"example_3",
+			args{[]int{9, 8, 6, 4, 2, 3, 5, 7, 1}},
+			0,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {