solve problem 5

Program.cs

@@ -97,8 +97,21 @@ namespace Euler {
   		return largest;
   	}
 
+  	static long Problem5() {
+  		for (long test = 20; ; test += 20) {
+  			for (int i = 2; i <= 20; i++) {
+  				if (test % i != 0) {
+  					break;
+  				}
+  				if (i == 20) {
+  			    return test;
+  			  }
+  			}
+  		}
+  	}
+
     static void Main(string[] args) {
-      WriteLine(Problem4());
+      WriteLine(Problem5());
     }
   }
 }