What is PI Approximation Day?

The date 22/7 or 22 July is PI Approximation Day because the formula 22/7 (22 divided by 7) gives a number which is close to PI.

What is PI?

PI is constant number with an unlimited amount of digits describing the relation between the diameter of a circle and the circumference.

Sounds technical, yes, but it is perhaps easier to explain it as follows:

Let's say you have a circle on the ground in front of you, and you walk straight through it from one outer line through the center of the circle and till you reach the other edge of the circle. When you measure it, you see it is 1 meter.

If you instead of walking straight through it would walk all the way around the circle until you get back to where you started, you would have walked exactly PI meters, or approximately 3,14159265359 meters.

While it can be tricky to remember all the decimales of PI, a simple (and often too simple) way of remembering PI is to to use the proximation of 22/7, which is accurate only down to the 2nd digit:

PI      = 3,14159265359...
22/7 =  3,14285714286...

PI Approximation Day is named after the formula - 22/7 = 22 July.

The real PI has it's own day on 3.14 or 14 March - more about PI Day here.