diff --git a/bit_manipulation/single_number.py b/bit_manipulation/single_number.py
new file mode 100644
index 000000000..0a59adb2d
--- /dev/null
+++ b/bit_manipulation/single_number.py
@@ -0,0 +1,30 @@
+def single_number(nums: list[int]) -> int:
+    """
+    Find the single number in an array where every other number appears twice.
+
+    Args:
+        nums: List of integers where every integer appears twice except for one.
+
+    Returns:
+        The single integer that appears once.
+
+    Example:
+    >>> single_number([4, 1, 2, 1, 2])
+    4
+    >>> single_number([2, 2, 1])
+    1
+    >>> single_number([1])
+    1
+    """
+    result = 0
+    for num in nums:
+        result ^= num  # Applying XOR operation
+    return result
+
+
+if __name__ == "__main__":
+    # Test cases
+    print(single_number([4, 1, 2, 1, 2]))  # Output: 4
+    print(single_number([2, 2, 1]))  # Output: 1
+    print(single_number([1]))  # Output: 1
+    print(single_number([5, 3, 5, 7, 3]))  # Output: 7