Saturday, September 27, 2025, is a very special day–mathematically speaking. That’s because the date’s numerals combine to form a rare numerical trick that even the most ardent math hater will appreciate.
If you write out September 27, 2025 as 09/27/2025 and eliminate the forward slashes, you get 9,272,025. The notable thing about that number is that it’s the square of 3,045. In other words, 3,045 times 3,045 is 9,272,025, as Fresno State University math instructor Howie Hua explains in a social media video, describing it as the “coolest mathematical date of our lifetime.”
But wait, there’s more! As you probably know, people in some countries write their dates out with the day before the month. In that case, 27 September, 2025 would be 27/09/2025. If we run the same trick as before, 27/09/2025 turns into 27,092,025. Lo and behold, that is the square of 5,205—5205 times 5205 is 27,092,025.
[ Related: How to bowl a strike—mathematically. ]
According to Timeanddate, this means September 27, 2025 isn’t just a square date, it’s a global square date, which occurs only eight times this century. The next global square date will take place on January 1, 2036, or 01/01/2036, which feels a bit like cheating since both versions yield 1012036 (1006 x 1006).
We’ve also recently passed another September date with an interesting association to squares. The numeral form of September 16, 2025 is 09/16/25, which works out to (3^2)/(4^2)/(5^2). Their consecutive square roots are an example of a Pythagorean triple, so September 16, 2025 was unofficially dubbed “Pythagorean Triple Square Day.”
Things get even stranger when you look at just the year 2025. It’s the square of 45 (45 x 45 = 2025), the square of the sum of all the decimal system digits (0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45, 45^2 = 2025), and the resulting number when you add up the cubes of those same digits (0^3 + 1^3 + 2^3 +3^3 + 4^3 + 5^3 + 6^3 + 7^3 + 8^3 + 9^3 = 2025).
If you’re waiting for a sign, this is it!
