Tuesday, January 11, 2011

Removing superstition with brute force - 5 fridays, saturdays and sundays in a month

Came across the following Facebook status update and thought it would be a simple thing to prove wrong.

I'm not superstitious, but this year July has 5 Fridays, 5 Saturdays and 5 Sundays.
This happens once every 823 years.

Or the alternative version:

Money bags

This year, July has 5 Fridays, 5 Saturdays and 5 Sundays. This happens
once every 823 years. This is called money bags. So, forward this to
your friends and money will arrive within 4 days. Based on Chinese
Feng Shui. The one who does not forward.....will be without money. 
  static void Main(string[] args)
  {
   int occuranceCount = 0;

   // Change to suit month of interest (1 to 12)
   int monthToTest = 10;

   for (int year = 1; year <= 2011; year++)
   {
    int fridayCount = 0;
    int saturdayCount = 0;
    int sundayCount = 0;

    for (int dayOfMonth = 1; dayOfMonth <= DateTime.DaysInMonth(year, monthToTest); dayOfMonth++)
    {
     DateTime dateToTest = new DateTime(year, monthToTest, dayOfMonth);
     if (dateToTest.DayOfWeek == DayOfWeek.Friday) { fridayCount++; }
     if (dateToTest.DayOfWeek == DayOfWeek.Saturday) { saturdayCount++; }
     if (dateToTest.DayOfWeek == DayOfWeek.Sunday) { sundayCount++; }
    }

    if (fridayCount == 5 && saturdayCount == 5 && sundayCount == 5)
    {
     occuranceCount++;
     Console.WriteLine(occuranceCount + " " + year);
    }

    
   }
   Console.ReadLine();
  }

Recent July's that meet the criteria: 2011, 2005, 1994, 1988, 1983, 1977, 1966, 1960, 1955, 1949, 1938, 1932, 1927, ...

This is the only time you see this phenomenon in your life.

Calendar August 2014  
 
August, next year, will have 5 Fridays, 5 Saturdays and 5 Sundays.  This happens only once every 823 years.  The Chinese call it 'Silver pockets full.  " So: send this message to your friends and in four days money will surprise you.  Based on Chinese Feng Shui.  Whoever does not transmit the message ... may find themselves poor
 
I obeyed (you never know).     

Recent August's that meet the criteria: 2008, 2003, 1997, 1986, 1980, 1975, 1969, 1958, 1952, 1947, 1941, 1930, 1924, ...