Add functionality to Exponent Function

src/exponent.c

@@ -1,5 +1,13 @@
 #include "exponent.h"
 
 int expI(unsigned int e, int num){
-    return 0;
+    int prod = 1;
+    if(e==0){
+        return 1;
+    }else{
+        for(int i = 1; i <=e; i++){
+            prod *= num;
+        }
+        return prod;
+    }
 }