diff --git a/math/sum_of_digits.cpp b/math/sum_of_digits.cpp
index 460bff691..42f0b5e82 100644
--- a/math/sum_of_digits.cpp
+++ b/math/sum_of_digits.cpp
@@ -55,9 +55,9 @@ void test2() {
  * all the test cases.
  */
 void test() {
-    //First test.
+    // First test.
     test1();
-    //Second test.
+    // Second test.
     test2();
     }