For last few days, I have been getting spam about the awesomeness and rarity of July with 5 weekends… something that is being claimed to happen once in 823 yrs. It’s all bullshit. Search on Google for “823 years July five weekends” something around it, and you’ll see great results. Once such URL is http://www.google.com/search?q=823+years+july+five+weekends. Even Times of India (the ad and sex newspaper of India) write this in their article here.
I happen to be a mathematician at heart. Reading these news, I got reminded of a calendar that I given to my father by an MR when I was in VIIth standard – that’s about 18-19yrs ago. The calendar was of some 150+ years. I was excited to get such a calendar. And then observing it closely and using some maths – though very trivial now – I realized the Gregorian Calendar repeats itself every 28yrs.
This is how… if there were no leap years, each year would have been for 365 days, that means, the calendar will advance by 1 day a week every year (365 mod 7 = 1), and hence will repeat every 7 yrs. Because every 4th year is a leap year, the reptition happens every LCM(4, 7) = 28yrs.
And in may be around 15-20minutes, I created a infinitely-usable calendar.
Ok. I admit, I have not taken into account 100yr factor… but it can be taken up.
Coming back to this 823yrs crap, and to verify my stats, I just went to TimeAndDate.com and this is what I got: http://www.timeanddate.com/calendar/?year=1983 as the calendar of 1983!(2011 – 28 = 1983).
Check it out closely… the month of July. What does it read — 5 weekends.
And so goes the calendars of 2011 +/- 28*n where n can be any number. Let’s just checkout the calendar of 2011 – 28 * 10 = 1973. Visit this: http://www.timeanddate.com/calendar/?year=1731 and you’ll know the truth.
Thanks for being enlightened! Yet another reason why I hate media… these uneducated people write news that impacts the masses. IMHO, these newspapers and media houses should be banned… donno about any criminal cases of misinformation or anything can be put against them!