# Overview

Tired of seeing all of those elitist 26.2 and 13.1 marathon/half marathon bumper stickers, but too busy with intellectual pursuits to take up that particular challenge? Sport your knowledge of (increasingly less) obscure mathematical concepts and show your support for the true Circle Constant Tau and Tau Day, where you get to eat twice as much pie, with these tau magnets!

Join tau activists Michael Hartl, Peter Harremoës, Joseph Lindenberg, and Bob Palais in promoting tau and help making learning mathematics and science just a little bit easier for the next generation of students.

Already tau is gaining in credibility with articles in Scientific American, ScienceLine.org and references in Wikipedia. But still, change is hard and we need to get the word out to the general public. What better way than encouraging people to Google 6.28 or navigate to tauday.com after scratching their heads in bemusement at your bumper for hours in traffic?

These magnets spoof the original 26.2 stickers, and include the first 174 decimal digits of tau in place of the traditional oval line.

# Tau Primer

Simply put, tau, or τ, is equal to circumference divided by radius, or C / r = 6.283185307179586..., which is 2π. Like pi, tau is an irrational and transcendental number. But tau, being based on the radius of the circle and not the diameter, is a more natural circle constant than pi, as many two-dimensional shapes have constant diameters, but only the circle has a constant radius.

In order to compensate for pi's inadequacies, many formulas include "2π", when they could easily substitute τ for better understanding by those studying mathematics. Other formulas, such as those for calculating radians halve natural denominators such as π/6 when τ/12 would be the more logical choice for calculating a 30° angle or 1/12 of a full circle.

Please read The Tau Manifesto by Michael Hartl for a much more thorough treatise on the benefits of tau over pi.