diff --git a/main.py b/main.py
index 3825247..27dd26e 100644
--- a/main.py
+++ b/main.py
@@ -1,12 +1,23 @@
 def factorial(n):
     """Calculates the factorial of a non-negative integer."""
-    # TODO: Implement the logic
-    pass 
+    result = 1
+    for i in range(1, n + 1):  # multiply numbers from 1 up to n
+        result *= i
+    return result
+
 
 def fibonacci(n):
     """Returns the nth number in the Fibonacci sequence."""
-    # TODO: Implement the logic
-    return None
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+    
+    a, b = 0, 1
+    for _ in range(2, n + 1):
+        a, b = b, a + b
+    return b
+
 
 def fizzbuzz(n):
     """
@@ -15,5 +26,14 @@ def fizzbuzz(n):
     - Multiples of 5 are "Buzz"
     - Multiples of both 3 and 5 are "FizzBuzz"
     """
-    # TODO: Implement the logic
-    return []
\ No newline at end of file
+    result = []
+    for i in range(1, n + 1):
+        if i % 3 == 0 and i % 5 == 0:
+            result.append("FizzBuzz")
+        elif i % 3 == 0:
+            result.append("Fizz")
+        elif i % 5 == 0:
+            result.append("Buzz")
+        else:
+            result.append(i)
+    return result