It depends how often October starts with a Saturday. As there are exactly 7weeks in a normal year, the begining day of the year, and therfore October, will cycle on by 1 day each year. In a leap year the begining day of the following year will have cycled on by 2 days. Therefore every sixth year the pattern repeats.
Incidently there are seven months each year with three repeating days so I really don't understand how the once in every 823 years thing came about.
My sister has just poster the 823 years thing on facebook and although she has done it as a half-joke, some people really believe this chain mail stuff. So I felt compelled to add my own little contribution of rationalisation to the internet. Please proliferate my nicely reasoned explanation just as much as idiots have bombarded you with requests to pass on their hopeless superstitions.
4 years
there 5 sundays,mondays,saturdays in every 200 years
Over the very long average, once for every seven years. And it's "often".
Never.
October 2011, December 2012, March 2014 for starters. In other words, how often does a 31-day month begin on a Saturday? Fairly often.
The odds are exactly 14.5%, which makes the average frequency once per 6.9 years.
December can have 5 Saturdays, 5 Sundays, and 5 Mondays only in specific years. This occurs when December 1st falls on a Saturday. In such cases, the month will have five instances of each of those days, which happens approximately once every 28 years, depending on leap years. The next occurrence after 2023 will be in 2034.
A December can have 5 Saturdays, 5 Sundays, and 5 Mondays if December 1st falls on a Saturday. This arrangement occurs in leap years, specifically when December 1st is a Saturday. Since December has 31 days, it includes five occurrences of each of those days in that scenario. Thus, this specific occurrence happens only in certain years.
Exactly 14% of all Decembers have five of each of Fridays, Saturdays and Sundays.
Every year has more than 5 Fridays, 5 Saturdays and 5 Sundays.
Exactly 14.25% of all July 23rds are Wednesdays. 14% are Sundays, 14.5% are Mondays, 14.25% are Tuesdays, 14.25% are Wednesdays, 14.5% are Thursdays, 14% are Fridays, and 14.5% are Saturdays.
The month of July has 5 Saturdays and 5 Sundays zerotimes in 2012.