Here are just a few of the mathematically special dates in 2015. I hope you’ll have fun celebrating them – I know I will!
NOTE: Answers to the questions asked below are in green. Kudos to Jim Waterman, Anita Dixon, and Rita Barger who submitted answers to some/all of them, and have won a FREE 2015 calendar -or photo- prize.
1. Pi Day 2015 !! We might as well start with the ONCE IN A CENTURY date! As you may remember, the common decimal approximation for pi is 3.14. So March 14 (3/14) (which also happens to be Einstein’s birthday!) is called Pi Day and is actually celebrated every year. (Various schools and classes go all out for this!) But, if you carry pi’s decimal expansion (3.1415926535 . . . going on forever without repeating!) a little further for your approximation, you get 3.1415 ! So, on Pi Day this year (3/14/15), there will be a SUPER once-in-a-lifetime celebration!!* Mark your calendar now! 🙂
*(Actually, there is a fairly good argument that would allow a similar SUPER celebration next year (2016) as well! Can you think of it?)
If you round the approximation above to 4 decimal places, you get 3.1416. This would certainly lend itself to a similar celebration next year!
2. Year-Product Days: Jan 15, Mar 5, and May 3. Look carefully at these three dates (1/15/15, 3/5/15, and 5/3/15), and you’ll note that the product [multiply] of the first two numbers (mo/day) is the third one (year). These are called “Year – Product Days”, and this is the second straight year we’ll have 3 of them. (How many were there in 2013? 2012?) There was only ONE such day in 2013 – namely 1/13/13. But there were SIX (!) in 2012: 1/12, 2/6, 3/4, 4/3, 6/2, and 12/1.
3. Consecutive Multiples of 3 Day: September 12. That day – 9/12/15 – is composed of three consecutive multiples of 3. We haven’t had one of these since MARCH 6, 2009, and we only have one more this century! (What is the day? 12/15/18 Why is that the last one? The next one would be 15/18/21, but there is no 15th month.)
4. June 28 – The BEST mathematical day each year! At least it’s MY favorite numerical day each year. There are TWO reasons to celebrate 6/28, each one significant!
A. 6/28 is 2-PI Day (Take 3.14 or 3/14, and double each number). Note that there is no 3-PI Day or any other similar multiple. (Why?) 3-Pi (or more) Day would call for at least a 42nd of a month (3×14).
B. 6/28 is the only day each year where the month (6) and day (28) are different perfect numbers!! (For a quick review of perfect numbers, visit the July Math Tidbit and note the material in red font. Visiting this link will also remind you why July 28 is special each year as well.)
5. Over 300 others! I mentioned that I happen to believe every day is special. If you’re so inclined, send in your birthday – or any other favorite – date, and I’ll let you know why it’s special! 🙂 [I’ll respond directly and -with your permission – list it and others in next week’s mailing.]
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