diff --git a/src/main/py/logarithmic_and_expo_and_root_calculations.py b/src/main/py/logarithmic_and_expo_and_root_calculations.py
index b4606f2..dc181e1 100644
--- a/src/main/py/logarithmic_and_expo_and_root_calculations.py
+++ b/src/main/py/logarithmic_and_expo_and_root_calculations.py
@@ -11,3 +11,7 @@ def potentiate(first_number, second_number):
 
 def logarithmize(first_number, second_number):
     return math.log(first_number, second_number)
+
+
+def logarithmize_dualis(first_number):
+    return math.log2(first_number)
diff --git a/src/test/py/logarithmic_ann_expo_and_root_calculations.py b/src/test/py/logarithmic_ann_expo_and_root_calculations.py
index d326a54..08cd50d 100644
--- a/src/test/py/logarithmic_ann_expo_and_root_calculations.py
+++ b/src/test/py/logarithmic_ann_expo_and_root_calculations.py
@@ -18,6 +18,9 @@ class primitive_calculations(unittest.TestCase):
     def test_8_log_3_equals_2(self):
         self.assertEqual(logarithmize(4, 2), 2)
 
+    def test_4_ld_equals_2(self):
+        self.assertEqual(logarithmize_dualis(4), 2)
+
 
 if __name__ == "__main__":
     unittest.main()