##### The times they are a-changinâ€™.

This post seems to be older than 17 yearsâ€”a long time on the internet. It might be outdated.

Christmas falling on a Sunday is rather unusual event. I would imagine that most people don’t even know the last time Christmas was on a Sunday. I would imagine even fewer people would take the time to figure out how often it does happen.

Well, that’s what I did last Sunday. The cycle described also applies to any given numerical day falling on any given day of the week. Here’s what I found:

The entire cycles actually takes 28 years. However, within that cycle, Christmas will fall on a Sunday in 11 years, then 6 years, then 5 years, and then 6 years again.

The easiest way to understand this is to write out the numbers 1-28 on piece of paper. In most years (i.e. non leap years), there are 365 days. This divides into 52 weeks plus one day. This causes the days to increment what day of the week they fall on by one. Thus usually Christmas fell on a Saturday the year before, it would advance one day and occur on a Sunday for that year, and next year it would fall on Monday. However, every four years, instead of moving one day, we move two days. To represent this, circle every four numbers, starting with 4 (you would circle 4, 8, 12, 16, 20, 24, and 28). Now count how many years it will take to advance 7 days (one week) and draw a line after you reach that year. You should end on “6”. Do the same thing until you reach the end of the list. You should come out with the pattern 6, 11, 6, 5.

The last time Christmas was on a Sunday was in 1994 (11 years ago). It will occur again in 6 years (2011, check your calendar), and then 2016, 2022, and 2033.

[tags]christmas, sunday, pattern, repeat[/tags]

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