Skip to content ↓
MIT student blogger Paul B. '11

Square Root Day by Paul B. '11

Your daily dose of nerd humor.

Did any of you notice today was a square root day? I didn’t, until I got a friendly email reminding me of this rare mathematical oddity:

“Today, 3/3/09, is square root day, which only occurs nine times each century. The last such day was five years ago, Feb. 2, 2004, which coincided with Groundhog Day. The next is seven years away, on April 4, 2016.”

This is part of why I love MIT – people here actually appreciate this kind of joke.

(In related news, Pi Day is only eleven days away. Get pysched!)

55 responses to “Square Root Day”

  1. Ryan says:

    Appropriately, our school’s math team just got its T-shirts today…

  2. Anonymous says:

    They actually mentioned it on the news where I live. Also, Pi Day falls the day before our spring break starts. Yippee!

  3. Oasis '11 says:

    I went to sleep around 4 AM, looked at my digital clock, and went “huh, 3×3 makes 9! how interesting!” (without having read any email about this).

    And then I see this!

    “MIT-ness” is really growing on me…I don’t know if this is a good thing or a bad thing .___.

    ps. People born in 2050 will be so shafted. They’ll experience their first “square root day” when they’re 31! (while most of us should have experienced ’01, ’04, ’09 by now – and if you’re older, then ’81)

  4. Oasis '11 says:

    On second thought, oops, I totally skipped 2064, LOL.

  5. Oscar V. 13? says:

    The fact that people actually appreciate the many meanings things might have and enjoy them either as a joke or a fact is one of the many reasons I love MIT!
    I hope I get accepted!

  6. Matt A. says:

    Ha!! raspberry Beautiful

  7. Anonymous says:

    I didn’t notice it’s square root day until i listened to the radio this morning.

    And both last year and this year, my prom will be on pi day!

  8. comboy says:

    things i did in last 4 hours
    i realized my birth date 28 march 1987
    my student id > 078942
    reverse birthdate > 7891382 (3 for march)

    789|1+3-8|2 = 78942

    my birth.year -my birth.month – my
    1987 – 3 – 28 = 1956
    1956 – 1 =1955 (einstein died)

    2009 – 1955 = 54 (fifty four years ago einstein died)
    5th of April 2009 (5/4/09)
    but he died in 18 april, anyway 5+4=9

  9. Ahmed says:

    Psh, today’s not a real square root day. The next one will be on 45/45/2025.

  10. Anon says:

    It totally is. Don’t know why I didn’t think of it. That’s an epic idea.

    Paul: which fraternity are you a member of?

  11. Anonymous says:

    It would be really fitting (and would also make me a happy camper) if the decisions were delivered to the anxious, nervous, and excited folks like us on the Pi day! Come on it’s also Einstein’s birthday smile.

  12. comboy says:

    i’m in group 3 in our technical report writing course
    my instructor’s office number is 303
    submitting draft is 33 percent
    our classroom is in mechanical engineerig room ME113
    this is the 3rd english course i’m taking

    linear algebra teacher office number is 239
    first day of classes this semester was 2 march 2009 (2/3/09)

  13. Paul says:

    @Anon: I’m in Phi Kappa Sigma, also known as Skullhouse on campus.

    @Infinity Anonymous: Cute. wink

  14. Chris Praley says:

    Oh my, pi day! Here in Severna Park we get intense at pi day. The English teachers celebrate it as well.

  15. Olisa says:

    I noticed but why the psych ask cos there is really noone that will appreciate that over here so I just zipped my air and made sure it did not smell in the sound in the rhythm of my “genius”
    How beautiful???!!! Square root day brings so much comment.

  16. sarfraz says:

    hi ,,,,,,,,,

    i am a high school student

    could u help me in become a MITiian in d future


    and about ur so called joke it wasn’t a joke after all , it was a fact

    anyways thank u for the fact

  17. ayaz says:

    Why is it that every applicant to MIT wants to learn how to hack?

    Unless my definition of hack is something else, feel free to let me know what this “hack” is

  18. jesline joy says:

    i wanna join MIT what are the admission procedures to get there??????

    plz help me

    join as an undergraduate for aerospace engg.

  19. Paul says:


    Applications are closed for this year, but you can apply again next year by going to

  20. The Truth says:

    Seems like your running out of things to blog about.. is there a quota on blog entries?

  21. Paul says:

    @The Truth:

    Actually, I have plenty of things I want to blog about: I’m just really busy with things like – you know – studying. Hopefully some longer entries will appear this weekend, when I have more time.

    In the meantime, I’ll continue to share the small but awesome things I observe throughout my daily life, which is why I blogged about this.

  22. Justin '13 says:

    on a very random note about repetition days…
    07/07/07 was my 16th birthday!

  23. Susana says:

    Sq root day? I admit, it’s kinky – but it isn’t as aesthetically beautiful as a symmetrical date. For example, 03-30-1991 (a.k.a. my d.o.b.) There was a nice one just past, 02-20-2002 but these babies are pretty rare; they only come six times in a century. Nothing beats pi day, though…

  24. I'm a square says:

    Wouldn’t 10-10-2100 technically be a square day?
    And for that matther, 11-11-2121 and 12-12-2144 would also be square days, so people born in the late 21st century will get to experience myriad square days!

  25. I would have been very worried if this wasn’t brought up in the MIT blogs…THANK you for bringing one of the best days ever to a beautiful end! (note the time-zone difference :/)

    œÄ day will be amazing as always, but come on. who’s not excited for 11:11 11/11 2011? too bad we’re no longer in the 12th century or we’d have a bunch of binary days…

  26. Sheila '13 says:

    Cool fact. I didn’t know/notice either until I saw my friend’s facebook status ^.^

  27. Colton says:

    @ Paul: Yes, I realize that Pi Day is coming and I’m already making arrangements to celebrate it in the chat on and to celebrate it in real life. Plus, it’s Einstein’s Birthday.

    Am I the only one thinking that Pi Day/Einstein’s Birthday should be an international holiday?

  28. Anonymous says:

    Yes Colton. I believe you’re the only one.


  29. Anonymous says:

    I was wondering why 4-2-02 and 9-3-03 weren’t included. That way, we could celebrate this wonderful holiday twice more every century! Then I realized that adding those two in would make 11 square root days instead of the current 9, and 9 is a perfect square.

  30. I turned 17 today!
    The offbeat sense of Humor of MIT people really made me apply for admission and of course the hacking!

  31. Banerjee says:

    That is so cool!! Its funny how people how so ignorant to notice these little things… people like me, for example.

  32. Chris says:

    Well, at least square root days are nicely spaced out through the centuries so if you’re reasonably lucky you’ll live through a few. The more obvious repetition days (07/07/07, etc) are all clustered at the beginning.

    It’s funny, I first noticed today because of an MIT friend of mine’s facebook status.

  33. jimmy '13 says:

    11 days………………….ahh…..glorious pi day………

  34. curious face says:

    Cool… Does infinite day exist if so when is it?

  35. Anonymous says:

    Curious face: It does. Last year, on August 8, you turned your calendar sideways.

  36. Anon says:

    Anon above me: you cannot be serious.

  37. Anonymous says:

    I thought it was pretty clever, if I do say so myself. raspberry

  38. Aly says:

    As interesting as that is, it’s not really a joke.

  39. Hey Paul,

    I have a question about a math class I should take in spring term that I was wondering if you could answer. I’m looking to go into Biological Engineering and I didn’t know which class would be better.

    I applied to MIT this year, and even if I don’t get in, I figure whatever you say will apply almost anywhere.

    Could I e-mail you my question?


  40. Paul says:

    @Jon: Sure, feel free to email me.

  41. Huzaifa says:

    square days–i never knew about them, they are quite cool actually, just like pi day.

  42. Oh yeah, Pi Day is coming! If only we lived in 1915, then it would actually be 3.1415. Or 1529. That would be so cool.

    And I completely agree with Colton. Pi Day/Einstein’s Birthday should be an International (or at least a better celebrated) Holiday.

  43. plz help me i want to tke admission in engeering courses offered by mit,,plz mail me on [email protected] or [email protected]

  44. @Colton and Others

    I dont understand how one can celebrate PI Day.
    Do throw some light on it!


    Any inside info or update on admission decisions?

  45. Philip says:

    Celebrate Pi day?
    1. Draw this logo everywhere.
    [Area of circle / Diameter]
    2. You’ve heard of alphabet soup. Now make numbers pie.
    3. Wear a Pi hat, something that looks like the greek letter (complete with earmuffs for this cold).

  46. comboy says:

    it’s also the day of Linux 1.0.0 release
    pi day and penguin day wink

  47. comboy says:

    Unfortunately they divide me by c
    if i multiply myself by c, I’m again 3/28

    Rydberg constant = 1.097373 m^-1
    c = 299792458 m/s

    Rydberg constant * c = 3.28

    multiplication by the speed of light, March 28, my birthday;
    unit in seconds, it’s my time

  48. Anonymous says:

    pfff PI DAY!

    Do you Americans know that not everywhere date format is mm/dd/yy?

    We have dd/mm/yy, which I find much more logical.

    we have no PI DAY then.

    uhm, maybe a kind of on 3rd january 2041 -> 3.1.42

  49. Anonymous says:

    ha! that’s why it’s so great to be american! we just HAVE to switch the month and day around in the date and use miles for our roads.

    i remember sqrt day. the vp of our math club kept yelling at me “today is sqrt day!” and i didn’t get it until i was about to go to bed…i was pretty disappointed in myself.

  50. Ahana says:

    I agree with Colton. Cummon…Einstein’s birthday! Pi Day!

    (The exclamation marks don’t really help, do they? Hmph.)

  51. CG says:

    Pi day… hmmm wouldn’t that be 3-14-16? :D
    I’m just angry because I only realized it was square root day on 3/4/09 -_-

  52. Anonymous says:

    @ ayaz

    Hacking at MIT is basically pranking.

  53. ron says:

    would love to email you the original info. on Square Root Day–I’m the “father” of it—dates back to 9/9/81 with a Washington Post story—we have a contest for this one running another week–please phone or email me—cell (650) 787-7381; home (650) 364-0652——-p.s. we’re less than 2 months from Odd Day, but that’s another story. Congrats on MIT–I’m “just” a Cal grad, but we do our best!!give me a call, Regards, ron smile

  54. ron says:

    p.s. Square Root Day is kind of like Pi day without the dessert—but we do have root beer in square glasses—can we email cartoons with this to you to include?? [email protected]—and after Odd Day (5/7/9), we have Romeo and Juliet Day–1/2/35–(“where four art thou”)—but that’s a few years out and I’m crossing fingers to be here then–let’s stay with the contest first—$339 in prizes. Do well and it’s kind of like MIT (Money In the Till)—can you folks pass our info on to other campuses??(by definition, other=non-MIT) smile

  55. lowell says:

    Square root day rocks!