Happy Pi Day… April 3?

by admin on March 14, 2015

Going off topic today!

Today is the “Pi Day” of the century, when the calendar reads 3/14/15 and the clock reads 9:26:53 am. We are supposed to be super excited about this because, after all, pi = 3.141592653…

Perhaps I’m just contrarian by nature, but I am not planning to bake a pie or join in any of the other Pi Day festivities. I do love the idea of a math holiday, but … numerology is not mathematics.

The thing that bugs me about Pi Day as a mathematician is that 3.141592653… is only the representation of pi in *base 10*. There is no reason to prefer this to other bases. It’s only important to us because we have 10 fingers. The most natural base for computers is base 2, where pi = 11.00100100001111… Then there’s base 3, where pi = 10.010211012222… And base 4, where pi = 3.0210033312222… Perhaps the coolest base for pi is base 16, because a formula was discovered a few years ago (by Borwein, Borwein and Plouffe) that allows us to compute any hexadecimal (base-16) digit of pi, say the billionth digit, without computing all the previous ones. There is no known formula that allows us to do this for base 10. The hexadecimal notation for pi is pi = 3.243F6A8885A3… By continuing to privilege base 10, we are discriminating against computers and polydactylic people!

My second objection to Pi Day is that it’s not even consistent. We aren’t using base 10. The first digit in 3/14/15 refers to a month, which is computed in base 12. The second digit refers to a day of the month, which is computed in base… uh… 30? 31? Depends on what month you’re talking about. The year, thank goodness, is base 10. But then we get to the clock time 9:26:53, where the numbers are computed in bases 24, 60 and 60 respectively. This isn’t mathematically meaningful, it’s a complete joke.

When *should* we celebrate Pi Day? Well, I would suggest that we do it when the year is pi months old. I think that is kinda sorta what the inventors of Pi Day had in mind. So the first question, obviously, is which version of a month should we use? Sidereal? Synodic? Tropical? Anomalistic? Draconic? I’m voting for the synodic month, 29.530588853… days. This definition of the month is the period from new moon to new moon, which is culturally the most meaningful. Also, this month is comparable to what most people think of as a month; the other ones are all in the 27-day range.

So pi synodic months, calculated to 11 decimal places, is 92.773080996… days. We will reach that landmark on April 3 at 6:33:14 pm. So… go on and celebrate today, if you must. But I will be eating my pie on April 3!

Addendum for math-y friends: I can’t resist adding this puzzle that I already posted on my Facebook page.

Recall that 1 astronomical unit is the distance between the earth and sun. Assume the earth’s orbit is circular, and assume that we define a month as exactly 1/12 of a year. Question: How many months does it take the earth to travel (1 + 1/4 + 1/9 + 1/16 + …) astronomical units in its orbit? (A piece of pie for the first person who answers correctly.)

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{ 5 comments… read them below or add one }

Franklin Chen March 14, 2015 at 9:09 am

My main issue with Pi Day, mathematically, is that Pi is wrong. I am waiting for the big Tau Day. http://www.tauday.com/


Brian Wall March 14, 2015 at 6:29 pm

Zombie Apocalypse Tournament, March 14 – 15, 2015

4 round Swiss system tournament.
Time Control: G/90; inc/30
Site: CSU campus in Ft. Collins. Lory Student Center, CSU Campus Rooms, Grey Rock Room.
Directions: I-25 to Prospect Rd. exit (exit 268) Drive west to College Blvd, turn right (north) Left on Laurel. Left on Meldrum. Lory Student Center is at south end of this parking lot. Free parking.
Open: Open to all USCF members and “Zombies” (see notes)
Entry fee: $45. Preregistration: $40. $10 discount for club membership with Fort Collins Chess Club, Denver Chess Club, or Colorado Springs Chess Club. Third family member free, the Sara and Tara rule.
Prizes: Based on entries. Bonus for non-zombie results over zombies $10 for win, $5 for upset draw.
Registration: 8:30 – 9:30am, Rounds: Saturday, 10:00am, 3:00pm. Sunday, 11:30am and 4:00pm. Late Sunday round due to the building opening at 11 AM..
Entries: Randolph Schine 8101 E. Dartmouth Ave. #15, Denver CO. 80231
Phone: Brian Wall – 720-483-6768 or Chris Peterson – 720-383-0477
E-mail: brianwallchess3@taom.com
First round starts at 10 AM but free pie will be served at 3/14/2015 at 9:26:53 AM following the sequence of pi.
Shirley Herman has asked for Peach Pie ala mode and Philipp Ponomarev has asked for Key Lime Pie.
Details: A zombie is any USCF player that has been inactive for 5 years (1 year for juniors). An adult player who has played a single tournament in 5 years also qualifies. Every zombie gets free entry fee, a 1 year CSCA membership and a 1 year USCF membership.
Zombies can win prizes like anyone else. Just show up and win. 15 Zombies limit. Zombies, this is a once in an undead opportunity. Rise from the dead. Live in chess again. Preregister at denverchess.com. This may be one of the strongest Colorado Chess tournaments in 5 years.
Don’t miss it!


Steve Merwin March 16, 2015 at 9:30 pm

That would be Pi months.


admin March 16, 2015 at 9:48 pm

Bingo! We have a winner.


Ashik Uzzaman March 23, 2015 at 8:04 am

It will be 2 * Pie * r . Here r = 1 astronomical unit. So 2 astronomical unit multiplied by pie.


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