diff --git a/py-revision b/py-revision
new file mode 160000
index 0000000..92e766d
--- /dev/null
+++ b/py-revision
@@ -0,0 +1 @@
+Subproject commit 92e766decd782f0a53b9fb10f004324a9da7187d
diff --git a/src/revision/mathematics.py b/src/revision/mathematics.py
index 78954c7..4b0c5b5 100644
--- a/src/revision/mathematics.py
+++ b/src/revision/mathematics.py
@@ -43,4 +43,9 @@ def hcfOfTwoNumbers(num1,num2):
     return hcfOfTwoNumbers(num2, num1%num2)
 
 def lcmOfTwoNumbers(num1,num2):
-    return (num1 * num2) // hcfOfTwoNumbers(num1,num2)
\ No newline at end of file
+    return (num1 * num2) // hcfOfTwoNumbers(num1,num2)
+
+def fibonacci(n):
+    if n <= 1:
+        return n
+    return (fibonacci(n - 1) + fibonacci(n - 2))
\ No newline at end of file
diff --git a/tests/unit/test_mathematics.py b/tests/unit/test_mathematics.py
index 499799f..3d6301b 100644
--- a/tests/unit/test_mathematics.py
+++ b/tests/unit/test_mathematics.py
@@ -1,6 +1,6 @@
 import unittest
 
-from src.revision.mathematics import sum, factorial, convert_temperature, lcm, hcf
+from src.revision.mathematics import sum, factorial, convert_temperature, lcm, hcf, fibonacci
 
 
 class Test(unittest.TestCase):
@@ -108,7 +108,21 @@ def test_hcf_of_given_multiple_numbers_is_8(self):
 
         self.assertEqual(result, 8)
 
-    
+    def test_fifth_term_of_fibonacci_is_5(self):
+        """
+        Test that sum of 3rd and 4th term is 5th that is 5
+        """
+        result = fibonacci(5)
+
+        self.assertEqual(result, 5)
+
+    def test_fourteenth_term_of_fibonacci_is_377(self):
+        """
+        Test that sum of 12th and 13th term is 14th that is 377
+        """
+        result = fibonacci(14)
+
+        self.assertEqual(result, 377)
 
 if __name__ == '__main__':
     unittest.main()
\ No newline at end of file