diff --git a/c-programming/math/opt_int_div.h b/c-programming/math/opt_int_div.h
index ca23cf0..bbf55e0 100644
--- a/c-programming/math/opt_int_div.h
+++ b/c-programming/math/opt_int_div.h
@@ -15,7 +15,7 @@
 
 // constants
 #define OPT_INT_DIV_ROUNDING                                                  \
-    /* 10^OPT_INT_DIV_TEST_PRECISION */                                       \
+    /* formula: 10^OPT_INT_DIV_TEST_PRECISION */                              \
     powl(10.l, (long double) OPT_INT_DIV_TEST_PRECISION)
 
 // helper functions