Mine

using System;

namespace ConsoleApp
{
    class Program
    {
        static void Main ( string[] args )
        {
            string[,] array = new string[20,4];

            /* This loop will go through all of the 20
             * students starting with 1, and ending with
             * 20
             */

            for( int x = 0; x < 20; x++)
            {
                /* This loop will go through all of the
                 * students (x) exams (y) and set
                 * the score for that students exam
                 */
                for( int y = 0; y < 4; y++)
                {
                    array[x, y] = "Student " + x + " Exam " + y + " ";
                }
            }

            for ( int x = 0; x < 20; x++ )
            {
                for ( int y = 0; y < 4; y++ )
                {
                    Console.Write( array[x, y].ToString() );
                }
                Console.Write( "\n" );
            }

            Console.ReadKey( true );
        }
    }
}