SpinningPromoter.cs

using System;
using System.Collections.Generic;
using System.Linq;

public static class Program
{
    public const int TotalTips = 61;
    private static void Main()
    {
        const int year = 2020;
        var dates = new List<DateTime>();
        for (int month = 1; month <= 12; month++)
        for (int day = 1; day <= DateTime.DaysInMonth(year, month); day++)
            dates.Add(new DateTime(year, month, day));

        Console.Clear();
        foreach (var date in dates)
        {
            var result = GetTip(date);
            Console.WriteLine($"{date.DayOfYear}: {result}");
        }
    }
    
    private static int GetTip(DateTime date)
    {
        // assume reading these from disk
        var tips = Enumerable
            .Range(1, TotalTips)
            .ToList();

        var result = tips[((date.DayOfYear - 1) % TotalTips)];
        return result;
    }
}