Pi Approximation Day is held on July 22 (or 22/7 in day/month date format), since the fraction^{22}⁄_{7} is a common approximation of π.

Larry Shaw created Pi Day in 1988. The holiday was celebrated at the San FranciscoExploratorium, where Shaw worked as a physicist, with staff and public marching around one of its circular spaces, then consuming fruit pies.

In celebration of Pi Day, Adafruit is offering 3.1415% off everything in the store! Check out with code “pi” for the discount, valid through 11:59pm 3/14/2012.

Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.

I’m partial to Tau day myself. Not for any philosophical or mathematical reason, but because Tau day results in even better discounts 😀