using System;

public class Program

{

    public static void Main()

    {

        var n = 30;

        var min = 1;

        var max = 4;

        var rnd = new Random();

        var ops = new [] {'*'};

        for(var i = 1; i <= n; i++)

        {

            var op = ops[0];

            var missing = rnd.Next(0,3);

            var a = rnd.Next(min, max);

            var b = rnd.Next(min, max);

            var c = a * b;

            var am = missing == 0 ? "__" : a.ToString();

            var bm = missing == 1 ? "__" : b.ToString();

            var cm = missing == 2 ? "__" : c.ToString();

            Console.WriteLine($"{am,2} * {bm,2} = {cm,2}");

        }

    }

}