diff --git a/287. Find the Duplicate Number/bit_manipulation/bit_manipulation.go b/287. Find the Duplicate Number/bit_manipulation/bit_manipulation.go
new file mode 100644
index 0000000..1b3093c
--- /dev/null
+++ b/287. Find the Duplicate Number/bit_manipulation/bit_manipulation.go	
@@ -0,0 +1,21 @@
+package problem287
+
+func findDuplicate(nums []int) int {
+	res := 0
+	for i := uint(0); i < 32; i++ {
+		countNormal, countDup := 0, 0
+		b := 1 << i
+		for j := 0; j < len(nums); j++ {
+			if j&b > 0 {
+				countNormal++
+			}
+			if nums[j]&b > 0 {
+				countDup++
+			}
+		}
+		if countDup > countNormal {
+			res += b
+		}
+	}
+	return res
+}