OOP2 Inner Class (C#)

Class Induk
/*
 * Created by SharpDevelop.
 * User: Joko
 * Date: 10/08/2015
 * Time: 16:47
 *
 * To change this template use Tools | Options | Coding | Edit Standard Headers.
 */
using System;

namespace Inner_Class_C_
{
public class Induk
{
public int penambahan (int a, int b) {
return a+b;
}

public int kali (int a, int b){
anak x = new Induk.anak();
return x.perkalian(a,b);
}

public class anak  {
public int perkalian (int a, int b){
return a*b;
}

public class cucu {
public int pengurangan (int a, int b){
return a-b;
}
}// end class cucu
}// end class anak
}// end class induk
}