This Oct has 5 fridays, 5 saturdays and 5 sundays.

Let’s think about this, a year can only start on one of seven days, so there are seven possible basic calendar years. Add leap years, and there are fourteen basic calendars. Period. And one of those calendars only gets used every 823 years? How would that be possible? It’s not of course, all fourteen calenders get cycled through regularly, in fact 2010 uses the exact same calendar as 1999.