diff --git a/dynamic_programming/Armstrong Number.cpp b/dynamic_programming/armstrong_number.cpp
similarity index 55%
rename from dynamic_programming/Armstrong Number.cpp
rename to dynamic_programming/armstrong_number.cpp
index 098c8c628..4dba89a27 100644
--- a/dynamic_programming/Armstrong Number.cpp	
+++ b/dynamic_programming/armstrong_number.cpp
@@ -1,16 +1,17 @@
-//program to check whether a number is an armstrong number or not
-#include <iostream.h>
-#include <Math.h>
-int main()
-{
+// Program to check whether a number is an armstrong number or not
+#include <iostream>
+
+using std::cout;
+using std::cin;
+
+int main() {
   int n, k, d, s = 0;
   cout << "Enter a number:";
   cin >> n;
   k = n;
-  while (k != 0)
-  {
+  while (k != 0) {
     d = k % 10;
-    s += (int)pow(d, 3);
+    s += d * d * d;
     k /= 10;
   }
   if (s == n)