When is National Pi Day 2025? What to know about Pi Day activities for kids, songs, movies, jokes, deals, snack ideas and more.

While the U.S. may have 11 official federal holidays, there are actually thousands of quirky, themed days that make the calendar a whole lot more fun! One of the best—and most delicious—is Pi Day.

Ellen Lindner / Investopedia A calendar spread is an options or futures strategy for simultaneously entering long and short positions on the same underlying asset but with different delivery dates.