diff --git a/Hacktoberfest2021/Count_ones_in_binary.cpp b/Hacktoberfest2021/Count_ones_in_binary.cpp
new file mode 100644
index 0000000..a7e8128
--- /dev/null
+++ b/Hacktoberfest2021/Count_ones_in_binary.cpp
@@ -0,0 +1,18 @@
+#include<iostream>
+using namespace std;
+int NumberOfOne(int n)
+{
+    int count=0;
+    while (n)
+    {
+        n=n & (n-1);
+        count++;
+    }
+    return count;
+}
+
+int main()
+{
+    cout<<NumberOfOne(237);
+    return 0;
+}
\ No newline at end of file