using System;

public class Program

{

    public static void Main()

    {

        int[, ] arr = new int[4, 5];

        int a = 0;

        Console.WriteLine("\n");

        for (int i = 0; i < arr.GetLength(0); i++)

        {

            for (int j = 0; j < arr.GetLength(1); j++)

            {

                a += 5;

                arr[i, j] = a;

            }

        }

​

​

        for (int i = 0; i < arr.GetLength(0); i++)

        {

            for (int j = 0; j < arr.GetLength(1); j++)

            {

                Console.Write(arr[i, j] + " ");

            }

        }

    }

}