diff --git a/algorithms/C/maths/primenum.c b/algorithms/C/maths/primenum.c
index c6f1d37c..8c764df5 100644
--- a/algorithms/C/maths/primenum.c
+++ b/algorithms/C/maths/primenum.c
@@ -10,6 +10,7 @@
 - Input | Output
 - 12    | It is not a Prime number
 - 31    | It is a Prime number
+- Time Complexity -> O(n/2)
 */
 #include<stdio.h>
 int is_prime(int n){