diff --git a/basics/04_functions/fibonacci_series.py b/basics/04_functions/fibonacci_series.py
new file mode 100644
index 0000000..5685381
--- /dev/null
+++ b/basics/04_functions/fibonacci_series.py
@@ -0,0 +1,15 @@
+def fibonacci(n: int) -> list:
+    """Return a list containing the first n Fibonacci numbers."""
+    if n <= 0:
+        return []
+    if n == 1:
+        return [0]
+    fib = [0, 1]
+    for _ in range(2, n):
+        fib.append(fib[-1] + fib[-2])
+    return fib
+
+
+# Example usage
+print(fibonacci(10))
+print(fibonacci(20))