diff --git a/11 November Leetcode Challenge 2021/18_findAllNos.py b/11 November Leetcode Challenge 2021/18_findAllNos.py
new file mode 100644
index 0000000..02d6011
--- /dev/null
+++ b/11 November Leetcode Challenge 2021/18_findAllNos.py	
@@ -0,0 +1,13 @@
+class Solution:
+    def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
+        
+        ans = []
+        n = len(nums)        
+        x = set(nums)
+        
+        for i in range(1, n+1, 1):
+            if (i not in x):
+                ans.append(i)
+                
+        return ans
+