diff --git a/fibonacci.py b/fibonacci.py
new file mode 100644
index 0000000..8392e0e
--- /dev/null
+++ b/fibonacci.py
@@ -0,0 +1,16 @@
+def fibonacci(n):
+    """Return the n-th term of the Fibonacci sequence (0-indexed)."""
+    if n < 0:
+        raise ValueError("n must be a non-negative integer")
+    if n == 0:
+        return 0
+
+    a, b = 0, 1
+    for _ in range(n - 1):
+        a, b = b, a + b
+    return a
+
+
+if __name__ == "__main__":
+    for i in range(10):
+        print(f"fibonacci({i}) = {fibonacci(i)}")