diff --git a/lesson_3/exercise_2.cpp b/lesson_3/exercise_2.cpp
index 1962836..74ed2b6 100644
--- a/lesson_3/exercise_2.cpp
+++ b/lesson_3/exercise_2.cpp
@@ -98,7 +98,7 @@ double Matrix::calculateDeterminant(Matrix &arr)
     }
     else if (arr.size() == 2)
     {
-        determinant = arr[0][0] * arr[1][1] + arr[1][0] * arr[0][1];
+        determinant = arr[0][0] * arr[1][1] - arr[1][0] * arr[0][1];
     }
     else
     {