September 16, 2025, is the only date that fits the definition this century. Here’s the specific math to add it all up: 3 multiplied by itself is 9, 4 squared is 16, and 5 squared is 2025. On top of ...

James is a published author with multiple pop-history and science books to his name. He specializes in history, space, strange science, and anything out of the ordinary.View full profile James is a ...

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.

MOST READERS will have encountered Pythagoras’s theorem about right-angled triangles—that the square on the hypotenuse is equal to the sum of the squares on the other two sides—at school. But the less ...