USA TODAY Pi Day might make losing an hour for the daylight saving time change a little easier – or at least more appetizing. Sunday, March 14 is both the annual ritual of changing clocks and the yearly celebration of the mathematical constant π (pi), which is the ratio of a circle's circumference to its diameter. The trillion-digit ratio is rounded to 3.14. But you don't have to be a math whiz to be acutely aware that Pi Day – not to be confused with National Pie Day held in January – equals deals and discounts on circular food like pizza, pastry and pot pies. Albert Einstein was born on Pi Day, and noted astrophysicist Stephen Hawking died on the made-up holiday in 2018.