History of Square Root Day


Historically, also known as “A Day for Squares” this holiday is celebrated either on years where the date and month, being equal numerically, can be multiplied together to equal the last two digits of the year… or on days  when multiplied against their numerically equal month produce a squared year number.

In simple terms, March 3, 2009, or 03/03/09 demonstrates that the square root of 09 is 03, or that 03 squared is 09.

This is not simply an American holiday, however. In other parts of the world, where the day is placed first and the month is second it is also celebrated. In England, for example, a foreign country that speaks a language very much like our own, today is 3 March, 2009, which squares up brilliantly.

When did this celebration start?

In the beginning…

That’s right, 0/0/00 marked the first observation of this holiday. It subsequently progressed numerically through the B.C. years, though some mathematicians insisted on expressing these dates as negatives, thus 4 B.C. = A.D. -4. Consequently, as no number multiplied by itself, even a negative number, can result in a negative number, the holiday was not as popular, except for those using imaginary dates.

Though originally a celebration for squares, in recent years diversity programs have promoted its popularity exponentially so that it is now celebrated amongst cubes. But it is not a secular holiday only, as you will note that it is also celebrated by a higher power.

The following is left as an exercise for the reader:

When will the next Square Root Day occur?

Bill Petro, your friendly neighborhood historian


  1. Chuck on March 4, 2009 at 8:19 am

    I will suppose that the next Square Root Day will not be for another seven years or so. It will occur sometime in the first week of April, though, I predict.

    But I will say I got totally lost in that paragraph that mentioned the first observation of this holiday. I understand the tongue-in-cheek stuff, but I think there is a typo on the math statement. I believe you meant to say “can result in a *negative* number” instead of positive. Then it would make sense to me.

    Other than that, this post is “squared away.”

  2. Bill Petro on March 4, 2009 at 10:23 pm

    Chuck, you are correct on both counts. Fixed.

  3. Deedee on February 15, 2014 at 8:34 pm

    Looking at the example, the next one that I can see easily would be, 04/04/16.

    • Bill Petro on February 17, 2014 at 2:03 pm


      Excellent observation.


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