February 2021 is an Extremely Rare ‘Perfectly Rectangular Month.’ Does It Only Happen Once Every 200 Years?
Did you know that February 2021 is a perfect rectangular month? This means that the first day of the month starts on a Monday and the last day of the month ends on a Sunday. Thus, the calendar has four rows of seven days, which makes a perfect rectangle with a length of 7 days and a height of 4 days.
Pretty cool, right?
And while a perfect rectangular month is considered extremely rare (some are claiming that such an event only takes place once every 200 years), how unlikely is it really?
Let’s explore!
For starters, is it possible that any other month can be a perfect rectangle month?
Every month’s calendar will always look like a jigsaw—except for February.
Why? Because February is the only month that has a number of days (28 assuming it is not a leap year) that is divisible by 7 (the number of days in one week).
For example:
January: 31 Days ÷ 7 = 4 with a Remainder of 3 Days
February: 28 Days ÷ 7 = 4 (*NO REMAINDER)
March: 31 Days ÷ 7 = 4 with a Remainder of 3 Days
April: 30 Days ÷ 7 = 4 with a Remainder of 2 Days
etc.
So, a perfect rectangular month can only happen in the month of February during a non-leap year (because there are 29 days in February during leap years).
Is February 2021 a Perfect Rectangle Month?
Yes! If you start the week on a Monday, you can see that February 2021 does not make a jigsaw shape. Rather, it is a perfect rectangle!
Note that you can also start the week on a Sunday and have a perfect rectangular year (which will occur in 2026!).
How Rare is a Perfect Rectangular Month?
And now for the big question…how often do perfect rectangular February’s occur?
It turns out that these perfect months are pretty rare, but not as rare as the once every two hundred years hype that is spreading around the internet these days.
These kinds of events actually occur about once per decade on average. The last perfect February occurred in 2010 and the next one will be in 2027.
Looking to Celebrate this Special February with Your Math Students?
If so, then add my free Perfect February 2021 Think-Notice-Wonder Math Writing Prompt for Grades 1-8 to your upcoming lesson plans!
▶ Click here to get your free PDF download!
New to Think-Notice-Wonder (TNW) Math Writing Prompts?
Bonus! Celebrate Black History Month in Your Math Classroom!
⇥ 11 Famous African American Mathematicians You Should Know About
February is Black History Month, a time to celebrate and honor the generations of African American men and women and their struggle to achieve citizenship and equal rights in American society.
