diff --git a/.devcontainer/README.md b/.devcontainer/README.md
index ec3cdb61de7a..7a2d7f4fe758 100644
--- a/.devcontainer/README.md
+++ b/.devcontainer/README.md
@@ -1 +1,45 @@
-https://code.visualstudio.com/docs/devcontainers/tutorial
+# Step by Step instructions for new user to use DevContainer
+
+## Step 1: Install Visual Studio Code
+
+Download and install **Visual Studio Code** from the [official website](https://code.visualstudio.com/).
+
+## Step 2: Install Docker
+
+Ensure **Docker** is installed on your machine. You can download it from the [official Docker website](https://docs.docker.com/get-docker/).
+
+## Step 3: Open a Project in Visual Studio Code
+
+Open the project you want to work on in **Visual Studio Code**.
+
+## Step 4: Install the Remote Development Extension Pack
+
+Install the **Remote Development** extension pack in **Visual Studio Code**. This pack includes extensions that enable you to work with development environments in containers, WSL, or SSH. You can find the extension pack [here](https://marketplace.visualstudio.com/items?itemName=ms-vscode-remote.vscode-remote-extensionpack).
+
+## Step 5: Open the Command Palette
+
+Press `Ctrl+Shift+P` (Windows/Linux) or `Cmd+Shift+P` (macOS) to open the **Command Palette**.
+
+## Step 6: Choose a DevContainer Configuration
+
+Type and select **"Remote-Containers: Add Development Container Configuration Files"** from the **Command Palette**. Choose a predefined configuration (e.g., Node.js, Python, etc.) or select **"Other"** to create a custom configuration.
+
+## Step 7: Customize the DevContainer Configuration (Optional)
+
+If you selected **"Other,"** customize the `devcontainer.json` file according to your project's needs, specifying the required tools, extensions, and settings for the DevContainer.
+
+## Step 8: Reopen the Project in a DevContainer
+
+Open the **Command Palette** again and select **"Remote-Containers: Reopen in Container."** Visual Studio Code will build the Docker image, set up the DevContainer, and reopen your project within the container.
+
+## Step 9: Work in the DevContainer
+
+You are now working within the **DevContainer.** Make your changes, write code, and use the integrated tools and extensions.
+
+## Step 10: Save and Commit Your Work
+
+Save your changes within the **DevContainer.** All changes are saved to your local workspace and are persistent across container restarts.
+
+## Step 11: Stop or Restart the DevContainer
+
+To stop the **DevContainer,** click on the bottom-left corner where it says **"DevContainer"** and choose **"Stop Container."** To restart, use **"Reopen in Container"** again.
diff --git a/bit_manipulation/missing_number.py b/bit_manipulation/missing_number.py
index 92502a778ace..b5376603c565 100644
--- a/bit_manipulation/missing_number.py
+++ b/bit_manipulation/missing_number.py
@@ -13,9 +13,13 @@ def find_missing_number(nums: list[int]) -> int:
         2
     """
     n = len(nums)
-    missing_number = n
-
+    number = nums[0]
     for i in range(n):
-        missing_number ^= i ^ nums[i]
-
+        if nums[i] != number:
+            missing_number = number
+            break
+        number += 1
     return missing_number
+
+
+# print(find_missing_number([0, 1, 3, 4]))