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.

Pi Day (March 14) is a day of global mathematical celebration, but it’s not the only numerically significant calendar date.

March 14 — a day you’re more likely than most others to eat — or throw — a pie and get a reduced price on your pizza. It’s all in celebration of pi (Greek letter π), the mathematical constant and ...