Its a Perfect Square

[taiwan_girl]

https://www.npr.org/2025/09/16/nx-s1-5535545/pythagorean-triple-square-day-9-16-25

Once a century, a very special day comes along. That day is today — 9/16/25.

Pi Day (3/14) often comes with sweet treats; Square Root Day (4/4/16 or 5/5/25, for example) has a certain numerical rhyme. But the particular string of numbers in today's date may be especially delightful to the brains of mathematicians and the casual nerds among us.

First, "all three of the entries in that date are perfect squares — and what I mean by that is 9 is equal to 32, 16 is equal to 42, and 25 is equal to 52," says
Next, those perfect squares come from consecutive numbers — three, four, and five.

But perhaps most special of all is that three, four, and five are an example of what's called a Pythagorean triple.

[Mik]

That’s so square.